Polish Grandmaster (GM) Jacek Stopa emerged as the sole leader with six points by getting the better of local GM Deep Sengupta in the seventh round of the SREI International Grandmasters Chess Tournament here Wednesday.
IM Siddharth Ravichandran upset top seed Surya Sekhar Ganguly (4).
Grand Master Ivan Popov of Russia and Levan Pantsulaia of Georgia are joint second with 5.5 points apiece.
In a sharp and interesting encounter which arose from a Reti opening, Stopa won a piece in the middle game and later consolidated his extra material to win in 33 moves.
After his unexpected reversal, the city-based Surya Sekhar needs to win the remaining three rounds to finish in the top pack.
Trying desperately to complicate the position in a King's Indian Attack, Surya, for once, was clearly inferior after the opening as his pieces lacked co-ordination and mobility. Ravichandran sacrificed the rook for bishop on move 20 and thereafter played precisely to win in 60 moves.
National women's champion WGM Mary Ann Gomes, too, had a bad day in office, as she succumbed to her first loss in the meet by going down to GM Valeriy Neverov of Ukraine.
Popov effectively utilised his passed pawn on d7 to win a rook ending against Marat Dhzumaev of Uzbekistan which arose from a Scotch defence.
Veteran GM Praveen Thipsay got the better of GM Sinisa Drazic of Serbia to total five points.
Top Board Results:
GM Samvel Ter-Sahakyan (5) lost to GM Levan Pantsulaia (5.5);
IM Jacek Stopa (6) bt GM Deep Sengupta (4.5);
GM Ivan Popov (5.5) bt Marat Dzhumaev (4.5);
GM Tornike Sanikidze (5) drew IM Anurag Mhamal (5);
IM Murali Karthikeyan (5) drew IM Mikhail Mozharov (5);
GM Vladislav Borovikov (5) bt IM Vahe Baghdasaryan (3.5);
IM Siddharth Ravichandran (5) bt GM Surya Sekhar Ganguly (4) ;
IM Prasanna Raghuram Rao (4) lost to GM Merab Gagunashvilli (5);
GM Valeriy Neverov (5) bt WGM Mary Ann Gomes (4);
N.R. Visakh (3.5) lost to GM R.R. Laxman (5);
GM Drazic Sinisa (4) lost to GM Praveen Thipsay (5);
M. Kunal (4.5) drew GM Levon Babujian (4);
Rishi Sardana (3.5) lost to GM Azer Mirzoev (4.5);
S. Ravi Teja (3.5) lost to Bahruz Rzayev (4.5);
GM Hovik Hayrapetyan (4.5) bt IM Himanshu Sharma (3.5)
