Kolkata, Sep 4 (PTI) Local Grandmaster Sandipan Chanda took the sole lead after Round Four of the 4th Kolkata Open Grandmaster Chess tournament at Alekhine Chess Club here today.
He accounted for fellow Indian GM Magesh Chandran Panchanathan in 35 moves.
Sandipan had the disadvantage of the black pieces but the local lad used the Semi-Slav defence to get a kingside attack going.
Magesh grabbed a queenside pawn and could not bring it back in time to save his unprotected king.
In the upset of the day, top seeded GM Shakhriyar Mamedyarov was shocked by the Vietnamese Grandmaster Le Quang Liem in a long-drawn game.
Mamedyarov played an irregular defence but it was inadequate and he soon had to defend against the double passed pawns created by his opponent on the queenside.