29 July 2016

Commentary: 2016 U.S. Championship, Round 4 (Yu - Yip)

This next commentary game is from round 4 of the 2016 US Championship (women's section).  I chose it because of the type of opening, which features an attempt by Black to directly challenge White's English Opening early on by exchanging in the center.  White (Jennifer Yu) makes some interesting decisions and notably lets Black (Carissa Yip) get a bit too much of a central hold, which gives Yip a slight advantage and the initiative.  White however starts to get the initiative back after a classic minority attack on the queenside, undermining Black's center and causing her to play too cautiously (see move 19).  Play then revolves around Black's weak c-pawn on the half-open file, which eventually is liquidated, but only after other weaknesses are created that give White a decisive queen move (36. Qf4!) that is an excellent illustration of the power of the queen to do multiple tasks at once.
[Event "ch-USA w 2016"] [Site "Saint Louis USA"] [Date "2016.04.17"] [Round "4.2"] [White "Yu, Jennifer R"] [Black "Yip, Carissa"] [Result "1-0"] [ECO "A16"] [WhiteElo "2157"] [BlackElo "2164"] [Annotator "ChessAdmin/Komodo 9"] [PlyCount "77"] [EventDate "2016.04.14"] 1. c4 Nf6 2. Nc3 d5 3. cxd5 Nxd5 4. g3 {by far the top choice in the database. White goes for immediate piece pressure in the center using the long diagonal.} (4. Nf3 {is the second most popular choice in the database. White avoids committing to the early fianchetto.}) 4... g6 5. Bg2 Nb6 6. Nf3 {in contrast with the move 4 variation, White has chased away the Nd5 before her own knight comes out.} Bg7 7. O-O {retaining maximum flexibility for as long as possible.} Nc6 8. d3 {White cannot reasonably play d4 here, due to Black's piece pressure on the center, but this more modest pawn advance releases the c1 bishop and asserts control over c4 and e4.} O-O 9. Rb1 {an interesting choice by White. Instead of playing a natural bishop developing move, for example Be3 or Bd2, as a follow-up to the previous move, she prefers to initiate queenside action immediately.} Bf5 {a somewhat puzzling square for the bishop, since it's left potentially exposed to harassment by a knight or by an eventual e4 or g4 push, should circumstances favor that. It is in a position to prevent Ne4, however, as a minor piece exchange on e4 would then give Black a 3-2 pawn majority on the queenside.} 10. h3 {this appears to be aimed at nullifying a potential future Q+B battery on the c8-h3 diagonal, after which White plays Kh2 to defend h3. White by this maneuver ensures that she keeps the Bg2 on the board rather than having Black try to exchange it.} (10. Be3 {alternatively would simply ignore Black's idea of exchanging the bishop, in favor of development. Play could continue} Qd7 11. Qd2 Bh3 12. Bh6 Bxg2 13. Kxg2 {and now White will be able to likewise exchange Black's bishop on the long diagonal, which is at least as valuable as its White counterpart.}) 10... e5 11. b4 {White presses ahead with her queenside expansion plan.} Nd4 12. Nxd4 $6 {this unnecessarily gives Black a strongly-supported central pawn, without sufficient compensation elsewhere in the position.} (12. Nd2 $5 $11 {looks a little passive, but it unleashes the Bg2 and keeps White's options open.}) 12... exd4 13. Ne4 { now White's knight lands on a nice central square, but it may have been of more use on c3, hitting b5 and d5.} Nd5 {Black now has a nicely centralized knight of her own.} 14. Bd2 {by this point there are no real alternative squares for developing the bishop.} c6 15. b5 {an easy move to play for White, since her main idea, starting with the 9th move, has been to push the b-pawn into Black's camp. This is a standard minority attack idea, seeking to undermine support for Black's center.} Qe7 {a safe-looking choice, although White's next move is also obvious and will help give her targets on the queenside.} (15... cxb5 16. Rxb5 {and White will have dynamic play on the queenside, although Black's strengths in the center balance this, along with the long-term 2-1 majority on the queenside.}) 16. bxc6 bxc6 17. Qc2 { pressuring the backwards c-pawn on the half-open file is now an obvious strategy for White.} Rac8 18. Rb3 {with the idea of dominating the open b-file. } (18. Qc5 $5 Qxc5 19. Nxc5 {would be a nice-looking positional gain for White, occupying c5 with a knight and opening up the long diagonal.}) 18... c5 { Black correctly looks to advance and then hopefully liquidate the c-pawn, which otherwise will be a long-term weakness.} 19. Rfb1 {consistent, but it gives Black the opportunity to resolve the situation with the c-pawn.} (19. Rc1 $6 {would fail to prevent the advance of the c-pawn, which tactically still works:} c4 20. dxc4 Nc3 21. Bxc3 dxc3 $17 {and White is cut off from protecting the c4 pawn, which Black will soon be able to take and thereby restore the material balance, while also having control over the center and a menacing passed c-pawn.}) 19... Nb6 {this appears to be a turning point in terms of the initiative. Instead of pressing forward, which is tactically possible, Black retreats and then focuses her attention elsewhere.} (19... c4 { and now play is similar to the above variation:} 20. dxc4 ({inserting} 20. Rb7 Qa3 {may be an improved version of the idea for White}) 20... Nc3 21. Bxc3 dxc3 $15) 20. Rb5 {adding sideways pressure against the c-pawn.} Rfe8 21. Bg5 { White is now the one making threats and forcing Black to play reactively.} (21. Rxc5 $2 Bxe4 $19) (21. Nxc5 $6 {the pin against the Qc2 will prove awkward after} Be5 $15 {and now Black threatens simply ...Bd6, also with ideas of possibly sacrificing on g3 in the future.}) 21... f6 $2 {a very committal move that is also unnecessary; there are several reasonable queen moves. Blocking the Bg7 effectively takes away a key piece from Black's game. Although Yip then moves to undo the block, the whole process leaves her more vulnerable and White well-positioned to exploit this.} 22. Bf4 Bxe4 23. Bxe4 f5 24. Bf3 { now it's obvious that White can support an h-pawn advance with her bishops.} Be5 {Black continues to attempt to exchange her way out of her difficulties.} 25. Bxe5 Qxe5 {it's interesting to see that the minor piece exchanges have had their desired effect on the kingside, but look at the remaining pieces. White's light-square bishop is huge, while the black knight is mostly ineffective. White's rooks are also very active and the c-pawn's weakness is magnified.} 26. Rc1 Nd7 27. Qc4+ {White's light-square dominance is well illustrated by this sequence.} Kh8 28. Rb7 Qd6 29. Rxa7 $18 Ne5 {still trying to exchange her way out of trouble, except now she is material down.} 30. Qd5 { a safe approach to handling the position.} (30. Qb5 {is the engine's suggestion, but it involves giving Black some more risky-looking activity, for example} Nxf3+ 31. exf3 {and Black has the e-file to work with and some potential kingside counterplay, although it does not work out in calculation, largely because the c-pawn is too vulnerable to capture.} Qc6 32. a4 $18) 30... Nxf3+ 31. Qxf3 {White's advantage is solid - a passed a-pawn and no real weaknesses, while Black still has the backwards c-pawn - and Black can do little about it.} Qb6 32. Rb7 Qe6 {targeting the one slightly weak point (e2) in White's position and supporting a c-pawn advance...which, however, will be problematic.} 33. Rc2 c4 $2 {this advance comes far too late now and out of desperation.} (33... Qc6 $18) 34. dxc4 {the simplest approach, just take the pawn.} Rxc4 35. Rxc4 Qxc4 {optically it looks like the position is not terribly worse for Black, with the weak c-pawn now gone, but now her exposed king position can be exploited by White's queen.} 36. Qf4 $1 {an excellent example of a decisive queen move that does multiple things. Useful ones include covering c1, getting on the open b8-f4 diagonal and pressuring the d-pawn. However, the most important threat is now to Black's h-pawn, which cannot be adequately defended from the Q+R combination.} Rxe2 {Black desperately tries to distract White, but to no avail.} 37. Qb8+ Qg8 38. Qd6 { with an unstoppable threat on the long al-h8 diagonal.} Re1+ 39. Kh2 1-0

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