Annotated Game #300: When the initiative turns

In analyzing this final-round tournament game, what struck me about it - other than yet again my failure to play the e3-e4 pawn break at the right time - was how quickly the game turned once I lost the initiative as White. The opening is unusual, but I come out of it in reasonable shape. The missed chance to play e3-e4 was the first inflection point in losing the initiative, but it really hurts only when my opponent targets the queenside pawn weaknesses I had ignored, once I had foolishly fixed the center by advancing the c-pawn. The collapse afterwards of White's structure is both quick and instructive.

[Event "?"] [White "ChessAdmin"] [Black "Class C"] [Site "?"] [Round "?"] [Annotator "ChessAdmin/Dragon 3.2"] [Result "0-1"] [Date "????.??.??"] [ECO "D00"] [PlyCount "50"] [GameId "2108267701342262"] {[%evp 0,50,25,26,13,20,5,-37,2,-3,12,-6,39,27,49,49,48,47,41,31,39,54,38,32,23,10,31,-3,1,-2,19,26,38,-45,12,-60,32,14,46,-99,-94,-466,-436,-461,-472,-516,-512,-549,-469,-565,-572,-586,-591]} 1. d4 d5 2. e3 Nf6 3. Bd3 Bg4 4. f3 {this takes away transpositional possibilities and moves the game into more creative territory. However it's tricky to play right, since the move f2-f3 always creates a weakness.} Bh5 5. c4 {a standard response to Black's early bishop sortie, hitting d4 and opening up the diagonal for White's queen.} c6 6. Nc3 e6 7. Nge2 {so far pursuing standard available development.} Be7 {now White has to make some decisions about how to proceed.} 8. b3 {this is a bit premature, since it's not clear where the Bc1 is best placed, and slow.} (8. Nf4 $5) (8. O-O {is probably the least committal route.}) 8... Bg6 9. O-O Bxd3 10. Qxd3 {I did not mind the exchange on d3, since it brings my queen to a good square.} O-O 11. Bb2 {consistent, if not the most dynamic move.} (11. e4 $5 {gives White some initiative in the center.}) 11... Nbd7 $11 {now Black is very solid.} 12. c5 {this idea backfires on me immediately. The d6 square is not particularly valuable now, and Black will now have the obvious plan of using the e-pawn lever.} (12. cxd5 $11) 12... e5 $15 13. Ng3 (13. b4 {immediately may be better, trying to stir up some counterplay on the queenside.}) 13... Re8 14. b4 exd4 15. exd4 b6 {this is possible due to the weak b4 pawn, which would be exposed after cxb6. White would lose time defending it and Black would gain even more positional dominacne.} 16. Bc1 {the general idea should be correct, repositioning the bishop, but the timing is poor.} (16. a3 $5 {protects the b-pawn and is probably simplest.}) (16. Nce2 {immediately also keeps the rooks connected.}) (16. Rfe1 {getting the rook into play.}) (16. cxb6 $2 Qxb6 17. a3 Ne5 $1 $17) 16... Nf8 {repositioning the knight is positionally justified, but this is too slow.} (16... a5 $1 {would immediately break things open on the queenside.}) 17. Nce2 {I play similarly slowly, however, so Black can catch up.} (17. Nf5 {immediately would be much better.}) 17... N6d7 18. Nf5 a5 {I missed seeing the possibility and the potential strength of this break, although I could do a reasonable job of containing it.} 19. Bd2 {after a long think, this seemed to be the least worst approach; however, my position quickly falls apart.} (19. cxb6 $1 {takes a lot of the sting out of the situation. For example} Qxb6 20. bxa5 Qxa5 21. Nxe7+ Rxe7 22. a4 $11) 19... axb4 $19 20. Nd6 {largely done out of desperation, but I was still hopeful that I was not yet losing.} Bxd6 21. cxd6 Ra3 $1 {now I'm lost, as the Ne2 is hanging after the queen is chased away.} 22. Qb1 Rxe2 23. Bxb4 Rae3 24. Rf2 Qh4 25. Rxe2 Rxe2 {and with the d-pawn also about to fall, it's past time to resign.} 0-1

Annotated Game #299: What the Caro-Kann is good for (part 2)

The below third-round tournament game is thematically similar to Annotated Game #294, in which White first presses Black - this time in a Panov variation of the Caro-Kann - then missteps, not sensing the danger. This is typically what Black is going for in the Caro-Kann overall, being patient and then seizing counterplay when it becomes available. Here I deliberately chose the most dynamic middlegame plan on move 13, after a long think, which is what opens up the opportunity later on for White to stumble.

[Event "?"] [White "Class C"] [Black "ChessAdmin"] [Site "?"] [Round "?"] [Annotator "ChessAdmin/Dragon 3.2"] [Result "0-1"] [Date "????.??.??"] [ECO "B14"] [PlyCount "56"] [GameId "2108266128867374"] {[%evp 0,56,25,16,59,71,77,47,47,24,10,3,32,20,39,35,25,13,4,-10,15,-17,-20,-17,-10,-14,-5,-2,0,0,14,12,3,3,3,0,0,-64,-12,-87,-96,-88,-94,-77,-73,-68,-26,-149,-213,-231,-231,-231,-238,-264,-204,-693,-669,-29993,-29994]} 1. e4 c6 2. d4 d5 3. exd5 cxd5 4. c4 {Panov variation.} Nf6 5. Nc3 e6 {this seemed to be the end of my opponent's opening familiarity.} 6. Nf3 Be7 7. Bf4 {a non-standard move here.} O-O {no reason not to castle here, although I had to check to see if the Nb5-c7 idea would work for White.} 8. Rc1 (8. Nb5 {and Black can simply ignore the supposed threat to play Nc7, as the Bf4 is vulnerable. For example} Nc6 9. Nc7 $2 Nh5 10. Nxa8 Nxf4 $19 {and White's knight is lost.}) 8... Nc6 (8... b6 {is the engine preference, preparing to develop the bishop on the long diagonal and restraining c4-c5.}) 9. c5 {I was not concerned about this advance at the time, since in analagous positions it's not a real threat. However, here it is worth preventing, since it creates a potential outpost on d6 which both the Bf4 and a future Nb5 could use.} Nh5 {not a bad idea to chase the bishop, but it leaves me a little underdeveloped.} (9... Ne4 $5 {and Black would welcome a trade on e4, which would expose the suddenly weak d4 pawn.} 10. Nxe4 dxe4 11. Ne5 Nxd4 $19) (9... a6) 10. Bg3 Nxg3 {this was perhaps a little too hasty, giving White the half-open h-file while removing a key defender on the kingside. It is still theoretically balanced, but it causes stress for me later.} (10... a6 {again would restrict the Nc3 from reaching b5.}) (10... f5 $5 {the engine considers White vulnerable to a kingside pawn advance, the immediate threat being f5-f4.} 11. Be5 g5 $11) 11. hxg3 Bf6 12. Bd3 g6 {I felt for defensive purposes it was better to blunt the bishop's diagonal, although ...h6 would be good as well.} 13. Qd2 Nxd4 {long think here. I can in fact get away with the pawn capture, which is the most dynamic choice and the engine agrees is best (slightly).} (13... Bg7 $11 {is the simpler way to play.}) 14. Qh6 Nxf3+ 15. gxf3 Re8 16. Qxh7+ Kf8 17. Kf1 {I had correctly calculated/visualized to this point. Black has several options here, I went with the one I could best visualize as limiting White's counterplay.} a6 {I decided prophylaxis was most important here, taking away the b5 square from my opponent and not letting the knight get into the fight that way.} 18. Ne2 $6 {looking to redeploy, but this gives me time to gain some piece activity. This type of error was why I chose this middlegame approach in the first place, since it gave my opponent more difficult problems to solve, and along with that more opportunities to go wrong.} (18. Kg2 $11) 18... e5 $17 {while a nice way to help restrict the Ne2, it more importantly also frees the Bc8 on the diagonal.} (18... Bg7 $17 {I also considered, with the point being that it opens up the diagonal for the Qd8's use. The engine considers it best; during the game, I was unable to confirm its safety during calculation, so chose the text move.}) 19. Nc3 Be6 {I had envisioned this defensive idea from move 17. Black has now consolidated the extra pawn.} 20. Kg2 {connecting the rooks and thereby renewing plans for the h-file attack, but with a loss of time.} Ke7 {finally getting out of the corner, although the king is not safe yet, with tactics having to be calculated.} 21. Qh6 {the queen of course was in danger of being trapped, with the path to h8 cleared for a rook.} (21. Bxg6 $2 Rh8 $19) 21... Rh8 $6 {this allows the queen to escape without consequence.} (21... g5 $1 $17 {keep the pressure on.}) 22. Qd2 $11 Qd7 {...Bh3+ looks dangerous, but I cannot actually make progess with it - until my opponent attempts to block it with} 23. g4 $2 {a decision made based on the fact that the g-pawn visually looks safe, being protected by another pawn. However, this is tactically incorrect.} (23. Bc2 Bh3+ 24. Kg1 {and the position is certainly awkward-looking for White's king, but there is no breakthrough.}) 23... Bxg4 $1 $19 {now the White king's shield is broken and Black is winning.} 24. Be2 (24. fxg4 $4 Qxg4+ 25. Kf1 Rxh1#) 24... Bh3+ 25. Kg1 {otherwise it's mate} Be6 {this was the simple approach for my still-stressed brain, at the time.} (25... Rad8 {is preferred by the engine, bringing the rook into play and protecting the d-pawn at the same time.}) 26. Kg2 (26. Rxh8 Rxh8 27. Bf1 $19 {would have forced Black to maneuver some more to get at the White king.}) 26... Rh5 (26... Bh3+ 27. Kg1 Rad8 {would free up the queen by reinforcing d5.}) 27. b4 $2 (27. Rxh5 gxh5 28. Rg1 Rg8+ 29. Kh1 {and there's no immediate win, although White will still lose once Black consolidates the center.}) 27... Bh3+ {now the bishop returns with deadly force.} 28. Kh2 Bf1+ $1 {and the queen will be able to come to h3 and then mate.} 0-1

Annotated Game #298: No pawn lever, no plan (part 2)

This next tournament game is another excellent illustration of the saying "no pawn lever, no plan" - unfortunately not the first time; see the first part here. As White, I did in fact have several good pawn breaks available - including the thematic Colle/Stonewall e3-e4 in the center - but did not play any of them at the correct time. After that, my position deteriorated rapidly under pressure until I made a visualization blunder. That's pretty much the story.

 

[Event "?"] [White "ChessAdmin"] [Black "Class B"] [Site "?"] [Round "?"] [Annotator "ChessAdmin/Dragon 3.2"] [Result "0-1"] [Date "????.??.??"] [ECO "D00"] [PlyCount "40"] [GameId "2108264990683174"] {[%evp 0,40,33,18,29,9,9,-7,13,-11,-12,-6,-9,-60,-35,-35,-21,-25,-29,-27,9,9,35,29,52,-18,1,-4,8,-7,-7,-66,-66,-70,-72,-73,9,-62,-69,-59,-4,-616,-597]} 1. d4 Nf6 2. e3 d5 3. Bd3 e6 4. Nd2 {choosing to prevent an early ...Ne4.} c5 5. c3 Nc6 6. f4 {reaching the Stonewall formation.} c4 7. Bc2 b5 {a popular move in the database, as Black quickly expands on the queenside, a logical follow-up to the previous move. However, it should not pose White any problems.} 8. Ngf3 {simple development in response.} Be7 9. O-O (9. e4 {is the key idea, reacting with the e-pawn lever after Black closes the center; it is already possible to execute.} dxe4 10. Nxe4 $11) 9... Bd7 $6 {putting the bishop on the long diagonal seems more logical.} 10. Ne5 a5 {my opponent is nothing if not consistent with pursuing queenside expansion plans.} 11. Qf3 $16 {long thought about a plan here. This is a good move, but is not followed up properly.} g6 {guarding against the f4-f5 advance.} 12. Qh3 {not a bad move, but White has multiple pawn breaks available that would cause more problems for Black.} (12. e4 {proceeds with White's play in the center.}) (12. a4 $5 {disrupts Black's queenside plans.} b4 {now allows the tactic} 13. Ndxc4 $1 {as the Nc6 is under-protected after the recapture on c4.}) 12... b4 13. g4 {an indication that I do not understand the needs of the position.} (13. e4 $1) 13... a4 $11 {now the queenside pressure is more meaningful (and concerning).} 14. g5 {the wrong pawn advance. It simply drives the knight away - to a decent square - and does not help with breaking through Black's defenses.} (14. f5 $11) 14... Nh5 {the knight is well-placed here to interfere with White's kingside plans, and can redeploy via g7 when needed.} 15. e4 $2 {played too late and now tactically flawed.} (15. Ndf3 $15) 15... Nxe5 {now either recapture is bad for White.} 16. dxe5 (16. fxe5 O-O $19 {and Black's king is safe, while White's advanced pawn shield and/or the queenside is about to collapse under pressure, with loss of material. One sample continuation:} 17. Nf3 b3 18. Bd1 a3 19. axb3 axb2 20. Bxb2 Rxa1 21. Bxa1 cxb3 22. Bxb3 dxe4 23. Nd2 Bc6 24. Bc2 e3 25. Qxe3 Bxg5 26. Qe1 Bxd2 27. Qxd2 Qh4) 16... Qb6+ $19 17. Kh1 Ng7 18. Re1 {I spotted the possibility of the queen penetrating on f2, but failed to calculate the consequences correctly.} Bc6 19. Nf3 Qf2 {this is actually not critical, and I recognized that, but then screwed up the calculation under pressure.} (19... Bc5 $19) 20. Nd4 $4 {this was a failure of visualization; the knight was the only piece protecting the Re1 and I did not change that piece status mentally, only focusing on the Bc2 and the possibility of Be3 trapping the queen. This is also an example of mental assumptions, specifically that normally the rooks are connected and therefore protected on the back rank.} (20. Qg3 {and things are still bad, but Black's queen has nothing better to do than retreat, as an exchange would release most of the pressure.} Qxg3 $2 21. hxg3 $15) 20... Qxe1+ 0-1

Annotated Game #297: Opening evolution

The previous tournament I felt I had played rather poorly at the time, but I felt better about my performance at the board following the last series of games analysis; even the opening blunder in game 3 yielded something useful. I also scored reasonably well, and better than statistically expected. This next tournament saw more or less the reverse, although in this first-round game I do well to remember and apply some lessons from the previous Exchange Caro-Kann game, including following through with the ...Bf5 idea. In keeping with the recent post on pawn sacrifices, the 15...b5!? idea is worth highlighting.

[Event "?"] [White "Class B"] [Black "ChessAdmin"] [Site "?"] [Round "?"] [Annotator "ChessAdmin/Dragon 3.2"] [Result "1/2-1/2"] [Date "????.??.??"] [ECO "B13"] [PlyCount "64"] [GameId "2108374627303490"] {[%evp 0,64,25,16,59,71,77,47,47,23,16,13,28,45,44,45,60,29,30,33,30,-18,12,-9,1,-16,-14,-14,10,-8,23,-22,6,-18,-10,-33,-31,-27,-26,-40,-33,-40,-50,-30,-41,-63,-56,-86,-92,-85,-70,-72,-57,-72,-54,-45,-45,-41,2,-5,-9,-6,-1,-8,0,0,0]} 1. e4 c6 2. d4 d5 3. exd5 cxd5 4. Bd3 {the Caro-Kann Exchange Variation.} Nc6 5. c3 Nf6 6. Bf4 g6 7. Nd2 {although this is the third most-played move in the database, it is the first time I have seen it.} Bf5 {I saw no reason to not proceed with the main idea of the ...g6 variation.} (7... Nh5 {is the engine move, and a common idea in this structure, but has relatively few games in the database as tests.}) 8. Qe2 Bxd3 {White has passed up the chance to exchange and inflict some pawn structure damage on Black - which, however, would have some dynamic compensation. I therefore correctly exchange light-squared bishops. White's minor piece is still stronger and therefore a good target, while Black's is definitely "bad", constrained by the pawns on d5 and g6.} 9. Qxd3 Nh5 (9... e6 {it's also fine to develop straightforwardly, with the bishop potentially going to d6.}) 10. Ne2 Bg7 (10... Nxf4 {it's better to simply carry out the threat immediately. Black's unopposed dark-square bishop may be useful in the endgame.}) 11. Nf3 O-O 12. O-O Nxf4 {now I see nothing better and exchange anyway.} 13. Nxf4 e6 {a solid approach, solidifying control of d5 and removing the weakness on e7.} 14. Rfe1 Qc7 (14... Qd6 {is a better square for the queen, as the f8-a3 diagonal is more valuable.}) 15. Ne2 a6 {a waiting move, primarily.} (15... b5 $5 {is a useful idea in this and similar positions. The point being that} 16. Qxb5 Rab8 {and White's b-pawn cannot be defended, while the rook penetrates to the 2nd rank.} 17. Qa4 Rxb2 18. Rab1 Rfb8 19. Rxb2 Rxb2 $15) 16. Ng3 {actually a worse square for the knight.} Rac8 {activating the rook.} 17. a4 {preventing ...b5, but now the knight can leap into action.} Na5 18. Qc2 Nc4 19. Re2 (19. b3 $6 Nd6 $15 {with pressure down the c-file.}) 19... Nd6 {improving the knight and opening up the c-file for the heavy pieces.} (19... b5 {is also now possible.} 20. axb5 axb5 {with now ...Ra8 and ...b4 as follow-up ideas.}) 20. Ra3 b5 {now I actually do find the correct idea.} 21. axb5 axb5 {threatening ...b4} 22. Rb3 $17 {preventing the b-pawn advance but abandoning the a-file.} Ra8 23. h4 {a good idea, to start some counterplay with threats due to the h-pawn "can opener" idea.} Ra1+ {I saw nothing better and it is certainly an effective move.} 24. Re1 Rxe1+ {as usual, exchanging decreases the tension and favors the defending side.} (24... Rfa8 $1 $19 {also finally getting the other rook into play.}) 25. Nxe1 Rc8 {now the threats are lessened.} (25... Ra8) 26. Qd3 {pressuring the b5 pawn.} Qc4 $6 {again with the trading down.} (26... Rb8 {would be more effective, overprotecting the pawn and allowing a follow-up with ...Nc4.}) 27. Qxc4 bxc4 28. Rb6 $15 {now White's problems are largely solved, with a more active rook screening his weak b-pawn.} Nf5 {this simplifies down to a draw quickly.} (28... Bf8 $5) 29. Nxf5 gxf5 {forced, otherwise d5 becomes weak.} 30. f4 Bf6 31. g3 Kg7 32. Nf3 Rc7 {and we both recognize that no progress can be made.} 1/2-1/2

Mastery Concept: Pawn sacrifices for piece activity

This is another in the periodic series of Mastery Concept posts, which highlight chess ideas at the Master level which are often ignored (or even unknown) at the Class player level. Typically these come from seeing a recurring theme in a recent series of game analysis, one which is echoed in other chess study materials that I'm using. Today's theme is the concept of choosing to sacrifice a pawn, in return for compensation in the form of piece activity.

One of my personal chess weaknesses has been an overly materialistic assessment of situations, which means I have inappropriately valued material over positional factors. This is a common phenomenon at the Class level. For example, players may hang onto a pawn for dear life, even if defending it cramps their position and gives their opponent a winning initiative, rather than deliberately jettisoning the pawn in return for freer and more active play for their pieces.

Another situation illustrated below is ignoring candidate moves that "lose" a pawn, without taking into consideration the benefits for the player's overall game. In some cases, these can even be very temporary sacrifices, or the pawn itself is "poisoned" due to a tactical response, which means ignoring the possibility - consciously or unconsciously - is a definite blind spot in the thinking process.

Finally, I'll make the observation that none of these pawn sacrifices lead to forced wins; these are not puzzles to be solved and the game is over. Rather, they are superior to other candidate moves, even if they only end up in a level position. This fact may also contribute to a Class player not considering them, if there is no obvious win or advantage that results.

Firstly from my own play, here are some clear examples. They are followed by a few master-level ones; if you go through any collections of annotated master games, you should be able to easily find more.

Annotated Game #296: The recurring idea of c4-c5, opening diagonals and the c4 square for pieces. I eventually play it, but under less favorable circumstances than I could have earlier in the game - this is also a recurring theme.

Annotated Game #295: The f-pawn sacrifice I should have played comes early enough to be considered a gambit, but the principle is the same - in return for the pawn, the rest of my pieces gain activity that provides full compensation.

Annotated Game #293: The move 15 possibility of playing c4 opens up activity for the dark-square bishop and queen, and works due to tactics (the hanging b-pawn is poisoned) that I should have further considered.

Annotated Game #291: Here's another freeing c4-c5 pawn sac idea on move 15.

Annotated Game #272: This shows the power of the e3-e4 pawn lever in Colle / Stonewall type positions, even when it is a (temporary) sacrifice.

A few Master-level examples, including from analysis:

Tarjan-Kosteniuk (2017) - 15. b4!?

From Bologan's Caro-Kann: A Modern Repertoire for Black (New In Chess, 2018) - analysis, King's Indian Attack; the d-pawn is given up by Black for piece activity, and it is also instructive to look at what happens if White tries to seize the d-pawn earlier.

[Event "?"] [White "Enter New Game"] [Black "?"] [Site "?"] [Round "?"] [Result "*"] [Date "????.??.??"] [PlyCount "32"] [GameId "2128221663227972"] 1. e4 c6 2. d3 d5 3. Nd2 e5 4. Ngf3 Bd6 5. d4 exd4 6. exd5 Nf6 7. dxc6 Nxc6 8. Nb3 O-O 9. Be2 Qb6 10. Nbxd4 Bc5 11. c3 Bg4 12. O-O Rad8 13. Qb3 Bxd4 14. cxd4 Qxb3 15. axb3 Rfe8 16. Bd1 a6 *

From John Nunn's Best Games 1985-1993, Batsford Chess Library, 1995; games 20 (move 19) and 22 (sequence starting with move 21)

[Event "World Cup"] [White "Nunn, John DM"] [Black "Portisch, Lajos"] [Site "Reykjavik"] [Round "8"] [Result "1-0"] [Date "1988.10.??"] [ECO "C73"] [WhiteElo "2625"] [BlackElo "2635"] [PlyCount "65"] [Beauty "8179769202696"] [GameId "1166636377100288"] [EventDate "1988.10.??"] [EventType "tourn"] [EventRounds "17"] [EventCountry "ISL"] [EventCategory "15"] [SourceTitle "CBM 010"] [Source "ChessBase"] [SourceDate "1989.06.01"] [SourceVersion "1"] [SourceVersionDate "1989.06.01"] [SourceQuality "1"] 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 d6 5. Bxc6+ bxc6 6. d4 exd4 7. Qxd4 Nf6 8. O-O Be7 9. Nc3 O-O 10. Re1 Bg4 11. Qd3 Bxf3 12. Qxf3 Nd7 13. b3 Bf6 14. Bb2 Re8 15. Rad1 Re6 16. Qh3 Qe8 17. f4 Rd8 18. Qe3 Nb6 19. e5 dxe5 20. f5 Rxd1 21. Rxd1 Re7 22. Ne4 Rd7 23. Nxf6+ gxf6 24. Re1 Qd8 25. Qe4 Nd5 26. Qg4+ Kh8 27. Bc1 Qf8 28. c4 Nb4 29. Qh4 Qd6 30. Qh6 Rd8 31. h3 c5 32. Re4 Rg8 33. Qxh7+ 1-0

[Event "Olympiad-28"] [White "Pinter, Jozsef"] [Black "Nunn, John DM"] [Site "Thessaloniki"] [Round "12"] [Result "0-1"] [Date "1988.11.26"] [ECO "E99"] [WhiteElo "2535"] [BlackElo "2435"] [PlyCount "92"] [Beauty "7220913783326"] [GameId "1166636396122112"] [EventDate "1988.11.13"] [EventType "team-swiss"] [EventRounds "14"] [EventCountry "GRE"] [SourceTitle "TD"] [Source "ChessBase"] [SourceDate "1994.03.01"] [SourceVersion "1"] [SourceVersionDate "1994.03.01"] [SourceQuality "1"] [WhiteTeam "Hungary"] [BlackTeam "England"] [WhiteTeamCountry "HUN"] [BlackTeamCountry "ENG"] 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Be2 O-O 6. Nf3 e5 7. O-O Nc6 8. d5 Ne7 9. Ne1 Nd7 10. f3 f5 11. g4 Kh8 12. Ng2 a5 13. h4 Nc5 14. Be3 Ng8 15. Rb1 Bd7 16. b3 b6 17. a3 a4 18. b4 Nb3 19. Nb5 Nf6 20. exf5 gxf5 21. Nc3 e4 22. g5 Nh5 23. fxe4 f4 24. Bd2 Nxd2 25. Qxd2 Qe8 26. Bf3 Ng3 27. Rfe1 Be5 28. Ne2 Nxe4 29. Bxe4 f3 30. Nef4 fxg2 31. Nxg2 Qh5 32. Qd3 Bg4 33. Re3 Qf7 34. Qd2 Qg7 35. Rd3 Rf7 36. Re1 Raf8 37. Ne3 Rf4 38. Ng2 R4f7 39. Ne3 Bh5 40. Rf1 Rxf1+ 41. Nxf1 Rf4 42. Qe1 Bd4+ 43. Kg2 Qe5 44. Ng3 Bg4 45. b5 Bf2 46. Qxf2 Bh3+ 0-1

From Journey to NM - Lightning Strikes Back blog, the round 4 game; technically this isn't master-level play, but it's close and White's sacrifice of the d-pawn for piece activity and an attack is an excellent example.

Don't Just Memorize, Understand! Two Key Moves in the London System - the full video (from Dr. Can's Chess Clinic) is worth watching for its principles, also containing a great pawn sacrifice idea in the central variation presented against the London System, which has a concrete tactical reason behind it.