On what turned out to be another hard fought day, Russian Evgeny Alekseev capitalised on an optical blunder and went on to beat former world junior champion Abhijeet Gupta, while top seed Radoslav Wojtaszek of Poland played out a draw with India's Krishnan Sasikiran.
At the half way stage in the category-18 six-player double round-robin tournament, Korobov still enjoys the cushion of a half point over Alekseev.
The Ukrainian with 3.5 points has three white games to come in the remaining five matches and has now emerged as a firm favourite for the crown.
Alekseev remains in pursuit of the leader just a half point behind. With his second victory coming in near-identical fashion like the first against Negi, the Russian took his tally to three points.
Wojtaszek and Negi stand joint third now with 2.5 points apiece, while Gupta slipped to fifth spot in rankings on two points.
Sasikiran is still at the bottom of the tables with 1.5 points from his five games in the Rs 1.2 million prize money tournament. (MORE)