Grandmaster Dibyendu Barua had a lucky day. He won a losing game on time basis against Prathamesh Mokal to emerge sole leader with 5.5 points in the men's section after seven rounds in the 40th National 'A' chess championship in Mumbai on Wednesday.

In the women's section, it was a turnaround, with WGM Aarthie Ramaswamy emerging sole leader with 4 points from five rounds, pushing overnight leader Nisha Mohota to the second spot with 3.5 points.

Pune lad Mokal almost ended up in shocking Barua. Playing with white, Mokal faced the French defence from Barua and decided to take the battle head on and went in for the advance variation of the French defence.

 The game progressed evenly with Mokal gaining good advantage as Barua had not castled. The Pune lad took advantage of this and on his 29th move captured the pawn on h7 thereby threatening the capture of rook on g8.

Barua played King on d7, allowing his Queen to support the threatened rook. The GM also saved the f7 pawn by playing his pawn to g6. Mokal spotted an excellent opportunity to offer his rook for Barua's Knight further imposing a series of checks which would have allowed Mokal to capture few more pawns.

It should have been a cakewalk for the youngster until fate struck him. Mokal had just eight seconds on the clock which he spent preparing for his next move. Finally he lost track of time and failed to move within the alloted time and lost the game on time basis.

However, the upset of the day was registered by debutant Arvind Shastry, who defeated IM S Kidambi in 61 moves.

On the other board, the match between two young GMs, Krishnan Sasikiran and Pendyala Harikrishna, who  shared the lead with Barua yesterday, ended in an expected draw with both the players agreeing to split the point after 37 moves.

The game was evenly paced with the players exchanging major pieces at regular intervals. In the course of the game, Hari had a bishop for Sasi's knight apart from rooks, bishop and six pawns each. There was not much initiative left in the game with the players now interested in a balancing act and agreed to end the game after just 37 moves.

In the women's section, Aarthie got the better of Y Pratibha to take the sole leader's position with four points.

In other games, WGM S Vijayalakshmi beat Swati Mohota with white pieces to earn a full point. Overnight leader Nisha Mohota, however, had an off day today and will face Dronavalli Harika tomorrow.

The eighth round in the men's section was in progress.

Results:

Men's (Round 7): P Harikrishna (5) drew with K Sasikiran (5); M R Venkatesh (4) drew with Praveen Thipsay (2); Arvind Shastry (3.5) bt S Kidambi (2.5); V Sarvanan (2.5) drew with S Soman (3); Abhijit Kunte (5) bt S Satyapragyan (2); R B Ramesh (3) bt Sriram Jha (1.5); Saptarshi Roy (3.5) drew with Suvrajit Saha (2.5); Neelotpal Das (4) bt G B Prakash (2.5); P Mokal (1.5) lost to Dibyendu Barua (5.5); S S Ganguly (4) drew with Lanka Ravi (4).

Women's (Round 5): D Harika (3.5) drew with Swati Ghate (1.5); Sai Meera (1.5) bt Krutika Nadig (0.5); R Aarthie (4) bt Y Pratibha (2.5); J E Kavitha (1.5) lost to Eesha Karvade (2.5); S Meenakshi (2) drew with Tania Sachdev (3); S Vijayalakshmi (2.5) bt Swati Mohota (1.5).