Grandmasters Krishnan Sasikiran and Pendyala Harikrishna share the lead with 3.5 points after four rounds in the National 'A' chess championship in Mumbai on Monday.

Woman Grandmaster D Harika, Woman International Master Nisha Mohota and WIM Aarthie Ramaswamy lead the field with 2.5 points after three rounds in the women's event.

In an interesting battle in the men's group, GM Dibyendu Barua defeated IM R B Ramesh to gain a whole point.

Barua, playing white, faced the Alekhine defence from Ramesh and eventually defeated him in a marathon battle which lasted 80 moves.

In the much-awaited battle between Sasikiran and veteran GM Pravin Thipsay, the latter, playing white, adopted the Ruy Lopez opening. To create a better position, he attempted an exchange sacrifice by giving his rook for Sasikiran's bishop. Sasikiran handled the position correctly, denying Thipsay the edge he was looking for. Time casted a shadow on the game with the players playing their moves, with a few seconds left on the clock, taking full advantage of the 30 seconds additional time which each player gets after every move.

Sasikiran managed his pieces well and forced Thipsay to resign on the 69th move.

In the match between overnight sole leader Harikrishna (Elo 2539) and in-form S Soman, who created the championship's first upset defeating Thipsay in round one, Soman managed to hold Hari for a draw there by accumulating 1.5 points.

IM Srirama, who was running low on form, showed no signs of improvement and lost to Arvind Shastry in a stunner.

M R Venkatesh scored a thumping victory over IM Satyapragyan.

At the end of third round, the women's group is jointly led by Harika, Nisha and Aarthie. Nisha defeated Krutika Nadig in a game which lasted 47 moves. Nisha developed a strong game and eventually won a piece to collect a full point.

The youngest national 'B' champion Harika won her encounter with Y Pratibha to take her tally to 2.5 points from three rounds. The world under-12 bronze medalist is surely making her presence felt in the tournament.

On another board, Eesha Karavade, playing black, faced Sai Meera. Eesha replied with e-4 against Sai Meera's Sicillian defence.

Eesha finally won in 57 moves scoring her first victory in the championship. In another match the sisters duo of Meenakshi and Vijayalakshmi settled for a short draw.