The Sinquefield Cup leaderboard experienced a shakeup in round four as both Americans suffered through, and ultimately lost, worse endgames.
Pre-round tournament leader GM Hikaru Nakamura breezed through the first half of the tournament, winning twice and nearly taking out GM Magnus Carlsen to make it a clean sweep (they drew in round three). Today was completely different against GM Levon Aronian, who blundered badly in their round one game.
"I took too many risks," Nakamura said. "All credit to Levon. He played well...I just gave him a free point."
Nakamura said he regretted his plan of ...a6 and ...b5. Aronian said better resistance could have been offered if Black matched 20. h4 with 20...h5, but "...h5 feels so sad. You give away this g5-square. His position is so unpleasant there."
"I'm just much worse," Nakamura evaluated the move. "Maybe a computer could hold it, but not a human."
Even so, an inventive piece sacrifice nearly allowed America's best player to liquidate all the pawns. Aronian was unimpressed with his own decision to trade queens and allow chances to hold in the endgame. He called the decision "silly...I have no explanation for it. I should have played Qd1 and won by attacking his king. The extra piece should help."
Nakamura spent nearly half of his remaining time trying to find a last-gasp salvo after 45. g3. The response 45...f3 nearly saves Black, but the plan to zigzag the pawns with ...e5 and ...e4 fails because he needs to spend a tempo on ...Kf6. For example, 46. Nd2 Bxh5 47. Bc2 Kf6 (to guard f5) 48. Bd1 and the e-pawn is too slow to connect with the loose pawn on f3.
Instead, Aronian wedged his knight on an inviolate outpost. When he finally reactivated it by heading for g5, Black's pawns stood to begin falling, and Nakamura capitulated.
Aronian and Nakamura have now played seven consecutive decisive games against each other in classical time controls. "I tend to complicate things, and as Black, I tend to lose," Aronian said of the curious stat.
The other American, GM Gata Kamsky, did not come out of the rest day with aggression, and was similarly ground down. He played the Exchange Ruy Lopez against Carlsen and lost as White for the first time against him.
"I thought perhaps he would be more ambitious," Carlsen said, adding that he thought Kamsky drifted after the opening. "I think he played a few mistakes from move 15-18."
Carlsen seemed especially critical of his own play as well. "At some point I lost control, but fortunately it was enough. Today in the fourth hour of play I was playing so badly. The same against Levon (Aronian) the other day - hesitating and burning huge amounts of time."
One oversight that would have converted sooner was the simplification 36...Nxb2 37. Rxb2 Ba3 38. Rc2 Rd2 39. Rf2 Rxf2+ 40. Kxf2 Bxc1 41. Rxc1 Rd2+, winning another pawn and establishing an insurmountable four-on-one queenside majority.
Both matchups went nearly five hours, the longest two games of the tournament. Carlsen conducted his normal on-air interview, but unlike the first few rounds, left the playing site expeditiously without answering questions from the growing contingent of media. There was also a big increase in the number of fans in attendance.
Kamsky, who began the tournament the most visibly excited of the quartet, was asked to explain how sometimes he has tournaments in which he struggles greatly. "It just happens," he said softly.
The two decisive games today make five winners out of eight games. Carlsen now leads with 3/4 and leapfrogs Nakamura, who is on 2.5/4. The two meet tomorrow, with Nakamura getting White this time around.
"I expected to be trailing him," Calrsen said on the live commentary. "It's a welcome change for me."
Aronian (2/4) takes White against Kamsky (.5/4).