Indian Grandmaster Krishnan Sasikiran suffered his second defeat at the Aerosvit International Chess tournament when he lost to Russian Grandmaster Sergei Rublevsky in the fifth round in Yalta, Ukraine.
Meanwhile, Ukrainian Sergey Karjakin shot into the lead with a fine victory over Alexei Shirov of Spain.
Karjakin, who was previously sharing the lead with Shirov and compatriot Vassily Ivanchuk, was the beneficiary as Ivanchuk was held to a draw by Russian Dmitry Jakovenko.
Ivanchuk is followed by a group of eight players sharing the third to 10th positions. The tournament is being closely fought and there is very little to separate the players.
The games -- Peter Svidler (Russia) vs Loek Van Wely (the Netherlands), Liviu-Dieter Nisipeanu (Romania) vs Lenier Dominguez (Cuba) and Alexander Onischuk (US) vs Pavel Eljanov (Ukraine) -- were long tussles, but without a decisive result.
Rublevsky played the popular Slav defence against Sasikiran and the Indian Grandmaster responded ambitiously by opting for sharp complications.
Sasikiran readily accepted pawn weakness on the kingside in an attempt to wrest the initiative. Rublevsky defended tenaciously and restricted his opponent.
The Indian's weak pawn structure proved to be the decisive factor in the position and Rublevsky won the game in 51 moves.
Karjakin showed great tactical resourcefulness in his victory over Shirov. The Ukrainian played the Spanish opening and failed to make much of the advantage of having white pieces.
Shirov equalised in the opening with the Neo Archangelsk variation and gained the initiative in the middle game. He sacrificed an exchange to gain an attack which looked very promising.
However, Karjakin combined defence with counter-attack and Shirov had no answer to his clever tactical play. The game ended after 45 moves as Karjakin won a knight to force his opponent's resignation.
Ivanchuk played the Pelikan variation of the Sicilian defense against Jakovenko and had little difficulty in equalising in the opening. He sacrificed a pawn on the 21st move to damage his opponent's pawn structure.
A bishop endgame was reached on the 32nd move and Ivanchuk had no difficulty in drawing the game despite his pawn deficit.
The game between Svidler and Van Wely ended in a draw after a theoretical duel in the English attack against the Sicilian Najdorf. Both players were well prepared in the opening and agreed to split the point after the exchange of queens.
Nisipeanu allowed Dominguez to escape with a draw. The Romanian played enterprisingly from the opening and succeeded in creating winning chances. However, he could not land the decisive blow and had to settle for a draw after 40 moves.
Results Round 5: Sergei Karjakin (Ukr, 3.5) beat Alexei Shirov (Esp, 2.5); Dmitry Jakovenko (Rus, 2.5) drerw Vassily Ivanchuk (Ukr, 3.0); Peter Svidler (Rus, 2.5) drew Loek Van Wely (Ned, 2.5); Alexander Onischuk (USA, 2.5) drew Pavel Eljanov (Ukr, 2.5); Krishnan Sasikiran (Ind,2.0) lost to Sergei Rublevsky (Rus, 2.5); Liviu-Dieter Nisipeanu (Rom, 1.5) drew Lenier Dominguez (Cub, 2.5)
The moves: (Krishnan Sasikiran Sergei Rublevsky)
1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 dxc4 5.a4 Bf5 6.e3 e6 7.Bxc4 Nbd7 8.00 Bb4 9.Qe2 00 10.e4 Bg6 11.Bd3 Bh5 12.e5 Nd5 13.Bd2 c5 14.Nxd5 Bxd2 15.Qxd2 Bxf3 16.gxf3 exd5 17.f4 cxd4 18.Rfc1 Re8 19.Bf5 Nf8 20.Ra3 Ne6 21.Rg3 Qh4 22.Bxe6 fxe6 23.Qxd4 Re7 24.Rcc3 Rf7 25.Rcf3 b6 26.Qc3 Raf8 27.Qc6 Qe7 28.Rg4 g6 29.Kg2 Kg7 30.Qc2 Qb4 31.Rh4 Rf5 32.Rfh3 h5 33.Rg3 Kh7 34.Rc3 Kh6 35.Rg3 Qe7 36.Rhh3 Qe8 37.Rg5 Rxf4 38.Rhg3 Rxf2+ 39.Qxf2 Rxf2+ 40.Kxf2 Kh7 41.b3 Qf8+ 42.Rf3 Qb4 43.Kg3 Qe1+ 44.Kh3 Kh6 45.Rgg3 Qxe5 46.Rf7 a5 47.Rb7 Qf5+ 48.Kg2 Qe4+ 49.Kf2 d4 50.Rxb6 d3 51.Rd6 Qf4+ 01. White resigns