Commentary: 2017 FIDE World Cup Tblisi, Round 1 (Ruiz Castillo - So)

I find it most helpful to group together studies of master (commentary) games and opening structures. I've been looking at the Classical Caro-Kann recently (see Nakamura - Liang) so selected for analysis the following game won by GM Wesley So as a useful follow-on. I've more or less randomly accumulated material for my commentary queue, based on reading reports of international events and seeing which games seemed most relevant, interesting and rewarding of more in-depth study.

So's victory and the choices made by both players along the way are well worth examining in detail. The first significant choice is on move 11. I expect White likely went into this variation with the idea of playing 13. a3, as an attempt to get material off the board and transition into an equal ending. However, So afterwards continually finds ways to pose small problems to his opponent and create more imbalances in the position. 

Some of the choices made by both players appear to have been more practical than objective, for example White's decision not to exchange rooks around move 30, but when playing a human in live chess, these are just as important to take into consideration. Other ideas, such as the ones behind So's moves 28 and 37, demonstrate a deep understanding of the dynamics and potential of the resulting positions.

White only makes a significant mistake on move 38, by allowing a tactic to win material, although on the previous move he sets himself up for it. This is a common psychological dynamic, as it is harder to un-commit from an idea (in this case centralizing the king) once it has already been played. By move 41, we therefore reach the point where classical annotators would simply end with "and now it is a matter of technique," but for those of us who could use some work on our endgame proficiency, So's technique is in fact worth following to its conclusion.

[Event "FIDE World Cup 2017"] [Site "Tbilisi"] [Date "2017.09.03"] [Round "1.1"] [White "Ruiz Castillo, Joshua Daniel"] [Black "So, Wesley"] [Result "0-1"] [ECO "B19"] [WhiteElo "2377"] [BlackElo "2792"] [Annotator "ChessAdmin/Komodo 13.2"] [PlyCount "118"] [EventDate "2017.??.??"] 1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Bf5 5. Ng3 Bg6 6. h4 h6 7. Nf3 Nd7 8. h5 Bh7 9. Bd3 Bxd3 10. Qxd3 e6 11. Bf4 {White's first significant decision in the main line of the Classical Caro-Kann. The alternative, Bd2, prevents Black's next, but has been considered less challenging.} Qa5+ 12. Bd2 {in olden times, the expected result would have been for Black to retreat with ...Qc7 and enter into more standard lines, rendering the Bf4/Bd2 decision essentially meaningless. GMs since the early 2000s have played this position more actively, however.} Bb4 {Black has a remarkable plus score (almost 54 percent) in the database after this move.} 13. a3 {this move is the third most played, but relatively rare. It essentially offers a transition to an equal ending and should therefore be viewed as a drawing attempt for White.} (13. c3 {is standard, after which Black does best to retreat with} Be7) (13. Ne4 $5 { starts off complications if Black does not wish to trade pieces, starting with} Ngf6 14. Nd6+ Ke7) 13... Bxd2+ 14. Qxd2 {at this point, Black scores well in the database both by trading queens or by keeping them on with either ...Qc7 or . ..Qd5.} Qxd2+ {So opts to head straight for the ending, having over 400 Elo points on his opponent and no doubt both greater experience and endgame skills.} 15. Nxd2 Ngf6 16. O-O-O {castling kingside would decentralize the king and leave the h-pawn weakened after the rook transfer, so White castles queenside.} Ke7 {Black feels no need to castle at all. The king is centralized for the coming endgame, covering the d6 square, and the rooks are connected.} 17. Nde4 {re-developing the knight, uncovering the Rd1 and offering another piece trade.} Rad8 {So develops the rook and implicitly declares he will be using it on the d-file, pursuing a central strategy.} 18. Rhe1 Nxe4 {So decides to simplify the task at hand, now that White has shifted his kingside rook over. This means that Black would gain a small initiative in the event of of a knight recapture.} 19. Rxe4 (19. Nxe4 Nf6 {now the h-pawn is threatened.} 20. Nxf6 gxf6 {and after ...Rhg8 Black will have a pleasant, if small, advantage in his rook activity. The doubled f-pawns are not a weakness that White can exploit and in fact help shore up Black's central control (e5 and e6 squares).}) 19... Nf6 {the knight goes to its best square with a tempo on the rook.} 20. Re5 {on the 5th rank the rook guards the h-pawn and is not badly placed, so Black harrasses it again.} Ng4 {also threatening f2.} 21. Re2 { retreating and protecting the f2 pawn at the same time.} Rd5 {now it is Black's turn to influence the 5th rank with a rook, provoking White's next.} 22. c4 Rd7 {the point of Black's maneuver was to make the d-pawn a better target for him. The position remains equal, but is easier to play for Black, who has more obvious targets (White's h- and d-pawns).} 23. f3 {pushing back the advanced knight and removing the f-pawn from its attack. This comes at the cost of the pawn's influence over g3 and e3.} (23. Nf5+ {is the choice of the engines, taking advantage of the pin on the e-pawn to drive the king away from its ideal square.}) 23... Nf6 24. Re5 {reoccupying the 5th rank, now that the rook cannot be driven away by the knight.} Rc8 {the king's rook finally gets into the game, So choosing to line it up against his opponent's king. One potential idea that results is the ...b5 pawn advance.} 25. Nf5+ {now White chooses to drive Black's king back. However, this is not as effective now, since the rook formerly on h8 has found freedom on the other side of the board. } Kf8 26. Ne3 Rcd8 {a simple but effective doubling of rooks against the d-pawn.} 27. Nc2 {with White's pieces more awkwardly placed and restricted, Black by this point has a slightly more concrete edge than simply enjoying an easier position.} b6 {increasing Black's control of the 5th rank and preventing ideas of Ra5, for example. At this point Black can be said to have the initiative as well, since White is running out of useful moves and will have to respond to Black's ideas.} 28. Rde1 {taking advantage of the fact that the knight is anchoring the pawn on d2, also removing the under-protected rook from any potential tactics involving the d-file.} Rd6 {this potentially frees up the d7 square for the knight and provokes White's next move. These types of ideas can be difficult for amateurs to spot. Often we look, in a too-narrow fashion, to always "do something" with the piece being moved. In this case, the rook itself is no better off on d6, but it accomplishes something useful for Black's other pieces.} 29. c5 Rd5 {So was evidently fine with allowing a trade of rooks. From a practical standpoint, a player with stronger technique usually finds it easier to win a single rather than double rook ending. This move further pressures the h5 pawn, so White is forced to deal with that threat over the next couple of moves.} (29... R6d7 {also looks good, maintaining the tension on the d-file. The square d5 is now also available for the knight.}) 30. cxb6 {White chooses not to exchange rooks and by doing so has to otherwise reinforce or remove his pawns on the 5th rank.} (30. Rxd5 { is what the engines advise.} Nxd5 {here Black's knight is unassailable on d5 and clearly superior to its counterpart, so White may not have liked that board picture when calculating.}) (30. g4 {played immediately lets Black gain positionally, after} R5d7 {followed by ... Nd5 and ...Ke7, centralizing the knight and king.}) 30... axb6 31. g4 R5d6 $15 {clearing d5 for the knight and keeping the rook on the 6th rank to defend the pawns from potential attack.} 32. b4 {gaining space on the queenside and helping blockade c5.} Nd5 {at this point, simply comparing the Black and White knights' scope for action shows why the engines show a noticeable (if not yet decisive) edge for Black.} 33. Kb2 {advancing the king towards the action and clearing the first rank for potential rook moves.} Nf4 {the better knight begins to make its presence felt, forcing White to respond to the fork threat on d3.} 34. R1e3 f6 {the engines prefer the idea of ...b5 here. However, squeezing White's rook has a certain appeal to it and So uses this to open the d-file.} 35. R5e4 e5 {now White has no choice.} 36. dxe5 Nd3+ 37. Kc3 {this intuitive-looking move, centralizing the king rather than moving it to the edge, in fact offers So a way to further imbalance the position.} (37. Ka2 {is the engines' choice.}) 37... fxe5 { similar to White's previous setup with his d-pawn, now Black's knight supports a central pawn against the pressure of two rooks. The difference is that Black's knight is much better placed than White's was, and Black's rooks are more dangerous. As we will see shortly, there is also a tactical point to the e-pawn's newly-won control of d4.} 38. a4 $2 {under pressure, White goes wrong. With this move, he evidently thought that the situation in the center was stable.} (38. Kb3 {and now Black no longer has the idea of a Nf2-d1 maneuver with check.}) 38... Nf2 $1 {now White loses material, since the Black e-pawn prevents the Re4 from escaping the knight's attack and covering the d1 square with Rd4.} 39. Rxe5 Nd1+ 40. Kc4 Nxe3+ 41. Rxe3 $17 {White has a pawn for the exchange, but with R+N versus a strong two rooks, this is not enough.} Rd5 { first shutting down potential White counterplay involving a queenside pawn advance. White's king is much more active than Black's, so allowing White to get a queenside passed pawn would be dangerous.} 42. Rc3 {lining up on the Black c-pawn.} Kf7 43. Ne3 {White has done a good job of reactivating the knight, but So can temporarily ignore it to resolve the situation on the queenside, while his Rd5 is still dominant.} b5+ {Black uses White's advanced king placement against him, forcing a pawn exchange.} 44. axb5 (44. Kb3 bxa4+ 45. Kxa4 Rd3 $17) 44... cxb5+ 45. Kb3 Rd3 {Black presses his advantage, keeping up maximum pressure on White's pieces.} 46. Nf5 Kf6 {the dominating placement of Black's pair of rooks means that he should avoid exchanging one, until he can get something concrete for it.} 47. Kc2 Rd2+ {the next sequences forces the White king away and keeps Black's rooks dominant.} 48. Kc1 Rd1+ 49. Kc2 R8d2+ 50. Kb3 Rd3 {White would now lose the f-pawn with a rook exchange. Note how Black has no interest in allowing any White attempts at counterplay.} 51. Ne3 Rb1+ {forcing the next sequence.} 52. Kc2 Rxc3+ 53. Kxc3 Ke5 {although the material balance is the same, Black effectively dominates the center (and White's knight) with his king. White's weak pawns are now more vulnerable as well.} 54. Nf5 Rf1 {Black is not afraid to trade pawns in this manner, since the rook will clean up on the kingside before White can do anything useful.} 55. Nxg7 Rxf3+ 56. Kd2 {note how White's king was effectively "boxed out" of the center and is essentially out of the action.} Kf4 {going after the g-pawn next. Black only needs to keep one pawn on the board, as White will then not be able to overcome Black's K+R combo, who can keep the knight and king away from it.} 57. Nf5 (57. Ne6+ {does not help, as after} Kxg4 58. Nd4 Rf7 59. Nxb5 Rb7 {with ...Rxb4 to follow, along with the fall of the h5 pawn.}) 57... Kxg4 58. Nxh6+ {a desperate attempt to eliminate Black's pawns, but now the knight will be trapped.} Kxh5 59. Ng8 Rf7 0-1