Diptayan, along with his city mate Deep Sengupta and eight other players is leading the field with two points.
Top two seeds Nigel Short of England and Sergy Fedorchuk of Russia scored quick wins to trail the leaders by half a point.
Diptayan played the Queen Pawn game against Adhiban and no pawn was captured or exchanged for the first 24 moves.
At this juncture, Adhiban made an unnecessary minor piece sacrifice and also an exchange sacrifice in the very next move.
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On the fourth board, Former under 14 world champion Vidit Santosh Gujrathi of Maharashtra dashed the hopes of West Bengal GM Neelotpal Das of PSPB in a pawn down position. He trapped Neelotpal's knight to win the game in 37 moves.
Former under 12 world champion Deep Sengupta of West Bengal played a long game today as well and finished again on the winning side against former national woman champion Swati Ghate of LIC. His rook and bishop were very active compared to the dormant pieces of Swati in the end game.
Former national champion of PSPB Abhijit Kunte's win over former under 16 world champion SP Sethuraman of PSPB is worth mentioning.
National women champion Mary Ann Gomes of Kolkata suffered a loss at the hands of Bangladesh GM Abdulla Al-Rakib.