Zonal champion Surya Shekhar Ganguly of PSPB emerged sole leader after a finely-crafted victory over S Vikramjit Singh of Manipur in the ninth round of the 41st National 'A' Chess Championship in Kozikhode on Tuesday.

Taking a breather from short and sometimes tame draws, the day witnessed nine decisive games, maximum so far in the championship, but springing a major surprise was Saptarshi Roy Chowdhury of West Bengal, who ended the dream run of Grandmaster Koneru Humpy with a tactical victory.

Chowdhary also made sure of his second IM norm in the process and now needs only to stretch his norm till game 11 when he will be crowned an International Master.

As things stand now, with 14 more rounds to go in the 24-players championship, Ganguly, on 7 points, has a slender half point lead over Humpy, who is followed by GM R B Ramesh of PSPB and Chowdhury on 6 points apiece.

Not far behind them are the PSPB duo of British champion GM Abhijit Kunte and Neelotpal Das on 5.5 points while a pack of six players, including GM Pravin Thipsay of BSB and PSPB's GM Sandipan Chanda, have 5 points each to their credit.

Saptarshi played his game with cautious aggression. With white, the Kolkata-based Railway employee, in the initial stages of the opening game, a rather off-beat Modern defence by Humpy, played quite solidly to ensure a better position.

Playing usually for a victory, Humpy spurned down a draw offer by Saptarshi but her position fell apart as she tried too hard for the full point. Saptarshi wrapped the issue with an elegant combination resulting in checkmate.

Ganguly, white, outplayed Vikramjit Singh in a Petroff defence game. The Manipuri fell under pressure in the center even after trading a couple of major pieces and decided to part with a pawn after which the extra material was converted into a victory by Ganguly.

In the only Grandmaster dual of the day, R B Ramesh drew with Sandipan Chanda without taking many risks with his white pieces. The opening was the Berlin defence by Chanda, who equalised quite easily with a famous plan in the Queen-less middle game and accepted the truce proposal in a level position.

In a major upset of the day, Commonwealth champion Dibyendu Barua of West Bengal went down to Vishal Sareen of LIC in a French defence game where the former played black.

Barua had a very complicated position on hand in the middle game but missed out on his chances before losing the ensuing endgame that might have been a draw with correct play.

Thipsay capitalised on a tactical oversight by debutant Arghyadip Das of West Bengal and won a pawn from a Sicilian Classical defence game. Once on top, Pravin, with white, scored the win quite effortlessly.

Neelotpal Das's better opening preparation came handy against veteran Hariharan, who sacrificed a piece without adequate compensation and lost the endgame, while double GM

norm holder Tejas Bakre cruised to a smooth victory against Suvrajit Saha of West Bengal.

Results (round 9): S Kidambi (4.5) drew P Harikrishna (5); S S Ganguly (7)beat S Vikramjit Singh (3); R B Ramesh (6) drew Sandipan Chanda (5); Vishal Sareen (4.5) beat Dibyendu Barua (4.5); M R Venkatesh (5) drew Abhijit Kunte (5.5); M Srinivas Rao (1.5) lost to Roktim Bandhopadhyay (3); T S Ravi (3.5) lost to Prathamesh Mokal (5); S Satyapragyan (4.5) lost to Sriram Jha (3.5); Saptarshi Roy Chowdhury (6) beat Koneru Humpy (6.5); Neelotpal Das (5.5) beat V Hariharan (2); Tejas Bakre (5) beat Suvrajit Saha (4.5); Praveen Thipsay (5) beat Arghyadip Das (2.5).