Kolkata: Grandmaster Li Quang Liem came back from behind to outskill local GM Surya Sekhar Ganguly and shoot into sole lead with six points after round seven of the 4th Kolkata Open Grandmaster Chess Tournament.
The Vietnamese employed the Caro-Kann defence and Surya, who was on the offensive from the beginning, slowly lost his position of strength at Gorky Sadan.
He got into acute time trouble and lost a couple of pawns after which it was all over.
Overnight leader GM Sandipan Chanda and GM Viktor Laznicka of the Czech Republic, who faced off on the top board, could not break their deadlock even though Sandipan defended a weak position throughout the game.
Both of them are in the second position alongwith GM Anton Filippov of Uzbekistan.
In an upset of the day, Filippov shocked British GM Nigel Short from the black side of a Giuoco Piano opening.
The Englishman tried the sharp Evans gambit and the Uzbek gobbled up the pawn and defended coolly.
Short then gave up a couple of more pawns on the queenside in his bid for an all out attack on the king but he could not succeed in penetrating his opponents defence and had to resign.
Top seeded GM Shakriyar Mamedyarov of Azerbaijan played an aggressive game to return to reckoning for a top spot. He defeated GM Magesh Chandran Panchanathan.