Young Indian Grand Master R Praggnanandhaa pulled off a huge upset, beating former world champion Veselin Topalov in the sixth round of the 18th Gibraltar chess festival to record his fifth straight win.
The 14-year old Chennai lad needed just 33 moves to put it across the Bulgarian. He had started with a loss against compatriot P V Nandhidhaa but since then he has been on a winning spree.
Praggnanandhaa, who recently won the world under-18 title, said: "It was very tough to prepare against him."
He is in second spot on five points with six other players and will take on Chinese GM Wang Hao in the seventh round.
Seventeen-year old Russian GM Andrey Esipenko jumped to sole lead with 5.5 points with a win over Georgia's Ivan Cheparinov with black pieces.
The Russian player would be unpaired in the seventh round as he decided to take a bye.
A bunch of players including Indians -- B Adhiban, K Sasikiran, Shardul Gagare, Karthikeyan Murali, last year's runner-up here, SL Narayanan, are in joint third place with 4.5 points.
Adhiban beat Gabriel Flom, while D Gukesh, the world's second youngest Grand Master ever, defeated Martin Percivaldi to move to four points.
Also winning were Karthikeyan Murali against Qi B Chen and Gagare over France's Maxime Lagarde.
Top-seed and world No.7 Shakhriyar Mamedyarov's moderate run continued as he was held to a draw by Indian GM Aryan Chopra. He is now on four points.
Meanwhile, second-seeded Frenchman Maxime Vachier-Lagrave, beat Fernando Peralta to register his third win in the tournament and take his tally to 4.5 points.
Swedish women's legend, Pia Cramling, a former world No.1, drew with Ukraine great Vassily Ivanchuk in 30 moves.
Important results after sixth round: Andrey Esipenko (5.5) beat Ivan Cheparinov (4.5); R Praggnanandhaa (5) beat Veselin Topalov (4); B Adhiban (4.5) beat Gabriel Flom (3.5); D Gukesh (4) beat Martin Percivaldi (3).
Shakhriyar Mamedyarov (4) drew Aryan Chopra (4); SL Narayanan (4.5) drew Daniil Yuffa (4.5); Maxime Vachier-Lagrave (4.5) beat Fernando Peralta (3.5); Shardul Gagare (4.5) beat Maxime Lagarde (3.5).