With her second straight win to start the tournament, Hou Yifan is the sole leader.

Four of the world’s top nine players are in the Grenke Chess Classic, including Magnus Carlsen, the World Champion from Norway. But after two rounds, none of them are leading the tournament. Instead, it is Hou Yifan of China, the world’s best woman player, who has a perfect score of 2 points, a full point ahead of most of the rest of the field.

Hou beat Georg Meier of Germany in Round 2. I really felt Meier’s pain in this game. Playing White, he obtained a very pleasant position against Black’s “hanging” pawns on the c- and d-files. But hanging pawns have some dynamic potential. It only took a couple mistakes for the tide to turn, and a couple more for White to be brutally checkmated. It reminded me of how I lost a similarly pleasant position against Jeffrey Xiong in the recent United States Championship.

Georg Meier vs. Yifan Hou
GRENKE Chess Classic | Karlsruhe GER | Round 2.1 | 16 Apr 2017 | ECO: E01 | 0-1
1. d4 Nf6 2. c4 e6 3. g3 d5 4. Bg2 Bb4+ 5. Nd2 O-O 6. Nf3 b6 7. O-O Bb7 8. b3 Nbd7 9. Bb2 Qe7 10. Ne5 Rfd8 11. Nd3 Bd6 12. e3 Rab8 13. Rc1 Ne4 14. cxd5 exd5 15. Re1 c5 16. dxc5! White gives Black hanging pawns pawns on the c- and d-files.
16... bxc5 17. Qc2 Rbc8 18. Nf4 Nef6 A necessary but unfortunate retreat for Black.
18... Ndf6 19. Nxe4 Nxe4 20. Rcd1 This is also no fun for Black.  )
19. Nc4! Energetic and strong.
19... Bc7 20. Red1! Now the pawn on d5 is very hard to defend.
20... Bxf4 Another move that Black did not want to make, but there was no choice.
20... Nb6 21. Nxb6 axb6 22. Bxf6 Qxf6 23. Nxd5 And White would be up a pawn and Black would have no compensation.  )
21. exf4 Ba8 22. Ne3 Meier's pieces are very active and his bishop pair dominates the board.
22... Qe6
22... d4? Black would like to play this, but it is not good because:
23. Nf5! Qf8 24. Bxd4! And the tactics work out in White's favor.
24... cxd4 25. Qxc8 Rxc8 26. Rxc8 Qxc8 27. Ne7+  )
23. Nf5?! A step in the wrong direction
23. f5! After this move, Black would have problems. The only way to maintain the defense of the d5 pawn would be:
23... Qd6 But this could be met by
24. b4! c4 25. Qa4! When Black cannot hold her position together.  )
23... Re8! 24. h3?
24. b4 White has not played precisely, but after this move, he would have still have had a clear edge.  )
24... d4! Black has accomplished her goal. The hanging pawns are advancing, the bad bishop on a8 will be exchanged for the good one on g2. The tide is turning quickly.
25. Bxa8 Rxa8 26. b4 Rac8 27. Qb1?
27. Re1! This move was best. White is at least equal after
27... Qxe1+ 28. Rxe1 Rxe1+ 29. Kg2  )
27... Ne4! 28. g4 g6 29. Nh4?
29. Nh6+ Kg7 30. bxc5 White had to try this, but it does not look like it is enough to survive.
30... Kxh6 31. Bxd4 Black's king position gives White some play for being down a piece.  )
29... Nxf2! White's position is hopeless now.
30. Kxf2 Qe2+ 31. Kg1 Re3 32. Qc2 Rg3+ 33. Kh1 Rxh3+ 34. Kg1 Qe3+ White resigned instead of facing 35. Qf2 Rh1, which is the only way to immediately avoid mate.

Fabiano Caruana of the United States, who lost to Hou in Round 1, bounced back to beat Arkadij Naiditsch of Azerbaijan. Caruana did it by exploiting of an error in the middlegame by Naiditsch.

Arkadij Naiditsch vs. Fabiano Caruana
GRENKE Chess Classic | Karlsruhe GER | Round 2.3 | 16 Apr 2017 | ECO: C24 | 0-1
1. e4 e5 2. Bc4 Nf6 3. d3 Nc6 4. Nc3 Na5 5. Nge2 Bc5 6. O-O O-O 7. Ng3 h6 8. h3 d6 9. Bb3 c6 10. Na4 Nxb3 11. axb3 Bb4 12. Bd2 Bxd2 13. Qxd2 d5 14. Qb4 b6 15. Nc3 c5 16. Qa3 d4 17. Nce2 a5 18. f4 Be6 19. Rae1 exf4 20. Nxf4 Nd7 21. Qa1 Qg5 22. Kh2 Ne5 23. Qd1 Rae8 24. Nge2 Ng6 25. Qc1 Qe5 26. Kg1 Nh4 27. g3 Ng6 28. Kg2 Qd6 29. Kh2 Ne5 30. Kg2 Black has a somewhat more comfortable position, but White is very solid. In an attempt to create some winning chances, Caruana opens the position.
30... f5! Black's pieces are more prepared for action than White's.
31. Nxe6 Rxe6!? Very enterprising.
31... Qxe6 This was a simpler continuation and would have been my choice. White's king is a little uncomfortable and Black has a space advantage. He would have a slight edge.  )
32. exf5 Qd5+ 33. Kg1? This loses
33. Kh2! This move was necessary. After:
33... Ref6 34. g4! White could hold his strong kingside pawn chain together. After:
34... Nf3+ 35. Rxf3 Qxf3 36. Qf4 Qc6 37. Ng3 After White plays Ne4, I believe he should have full compensation for being down an exchange.  )
33... Ref6! 34. Nf4
34. g4 Nf3+ 35. Rxf3 Qxf3 36. Qf4 If the White king were now on h2, he would be fine. But in this position, the problem would be:
36... Qxh3  )
34... Nf3+! 35. Kf2
35. Kh1 Qb7 Very effective. White cannot avoid catastrophic losses.  )
35... Qxf5! 36. Kxf3 Qxh3! White will soon lose his extra piece and then just have an exposed king with no compensation.
37. Re4
37. Rg1 Rxf4+  )
37... g5 38. Ke2 Qxg3 Black will soon be down two pawns, with no compensation. While Caruana did recently lose a game in which he had a two-pawn advantage, he did not do that this time.
39. Rf3 Qg4 40. Qh1 Rxf4

Matthias Blübaum of Germany defended a pawn down, opposite-colored bishop ending for a very long time against Maxime Vachier-Lagrave of France, but ultimately succumbed to the pressure. There would have been four decisive results in Round 2, but Carlsen missed a win against Levon Aronian of Armenia. I’m sure Carlsen will not be happy with himself for this one:

Magnus Carlsen vs. Levon Aronian
GRENKE Chess Classic | Karlsruhe GER | Round 2.2 | 16 Apr 2017 | ECO: C88 | 1/2-1/2
1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 O-O 8. a4 b4 9. d3 Bc5 10. c3 bxc3 11. bxc3 Rb8 12. Bg5 h6 13. Bh4 g5 14. Bg3 Nh5 15. Nbd2 Nxg3 16. hxg3 Qf6 17. Nc4 d6 18. Ne3 Be6 19. Bxe6 fxe6 20. Qc2 h5 21. Rab1 Rxb1 22. Rxb1 h4 23. gxh4 gxh4 24. Rb7 h3 25. Rxc7 hxg2 26. Qe2 Ne7 27. Ne1 Rb8 28. Qg4+ Ng6 29. Nf3 Rb2 30. d4 exd4 31. e5 dxe5 32. Nc4 Rb1+ 33. Kxg2 e4 34. Qxe4? Carlsen misses his chance. He was under some pressure, but not that much- I would have expected him to find the winning maneuver:
34. Nfe5! The knight on g6 is lost. Black can try to create counterplay with his pawns but it will be insufficient:
34... e3 35. Rf7! Perhaps this is the move Magnus missed?  )
34... Nf4+! 35. Kg3 Ne2+! Well calculated. White cannot easily avoid a perpetual check.
36. Kg4
36. Qxe2 Qg6+ 37. Kf4 Qf5+ 38. Kg3 Qg6+  )
36... Qf5+! 37. Qxf5 exf5+ 38. Kxf5 White did avoided the perpetual check, but at a high cost. With the queens off the board, the Black king is safe for a move or two, and after:
38... dxc3! He has a very dangerous passed pawn. Carlsen managed to create some problems for Black, but none that he was unable to resolve.
39. Rxc5 c2 40. Rc8+ Kg7 41. Rc7+ Kg8 42. Kf6 Rg1 43. Nxg1 c1=Q 44. Nxe2 Qh6+ 45. Ke7 Qh7+ 46. Kd6 Qd3+ 47. Kc5 Qxe2 48. Kb6 Qxf2+ 49. Kxa6 Kf8 50. a5 Ke8 51. Nb6

Hou faces Carlsen in Round 3 on Monday, and though she has White, she will most likely have an uphill battle in trying to maintain her perfect score and her lead.

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Samuel Shankland is a United States grandmaster ranked No. 4 in the country. He is a professional player and recipient of the Samford Fellowship in 2013, the most prestigious award in the United States for young chess players. He was also a member of the team that won the gold medal at the 2016 Chess Olympiad. He is at @GMShanky on Twitter, has his own site, and is also on Facebook.