Kolkata: Uzbek Grandmaster Marat Dzhumaev emerged sole leader with 4.5 points after fifth round of the SREI International Grandmasters Open Chess Tournament here on Monday.
But it was IM Swayams Mishra who hogged the limelight by upsetting American GM Roset Ziatdinov in just 28 moves in a King`s Indian defence.
GM Valeriy Neverov of Ukraine sacrificed a bishop against GM Dzhumaev to break open the latter`s kingside as the Uzbek defended with precision to win in the game in 43 moves.
On the top board, second seed, GM Ivan Popov of Russia was locked in an interesting duel against compatriot IM Mikhail Mozharov but neither side could make headway in rook and bishop versus queen ending.
Top seed Surya Sekhar Ganguly tried keep the sparks flying in a same-coloured bishop ending against Neelotpal Das but only to settle for a draw in a duel between the two city-based GMs.
In another upset of the day, IM Prasanna Raghuram Rao held GM Azer Mirzoev of Azerbaijan.