Top seed Grandmaster Koneru Humpy scored a thumping victory over former World champion Antoaneta Stefanova of Bulgaria and was helped by other results to come back in the joint-lead at the end of the 10th round of the IS Bank Atatyurk Women's Grand Prix chess in Istanbul on Thursday.

Humpy demonstrated brilliant attack and outplayed Stefanova, but, importantly for her, French girl Marie Sebag came good against overnight leader Zhao Xue of China while second seed Yifan Hao of China was also held to a draw by Elina Danielian of Armenia.

Humpy thus joined Zhao and Yifan in the lead on 7.5 points out of a possible 10.

Now the last round will determine the fate of the three leaders.

Elina Danielian holds fourth place with seven points and is the only one within striking distance of the leaders.

The last round pairings give an edge to Yifan, as she is playing an out-of-form Shen Yang of China.

Zhao has a tough nut to crack in Elina while Humpy will have to beat Marie Sebag in order to retain her chances of a first place finish.

Humpy displayed top form when it mattered and Antoaneta did not have a clue as to what hit her in a Slav defense game where the Indian played white.

Both players castled on the queen side and just when it looked as if it was a normal position, Antoneta slipped and allowed a dangerous queen manoeuvre on the 15th move following which she was forced to part with a rook for Bishop.

Humpy increased her advantage with almost each passing move thereafter. The Indian brought her rooks together on the queen side to launch an attack against the king and succeeded in quick time as Antoaneta tried to get some counter play.

It was all over in just 30 moves.

Marie Sebag struck form against Zhao in a Semi-Slav Botvinnik variation game. Showing her intentions to go for a bloody battle Marie took the pawns on offer early in the game and defended quite well to steer the game to a better ending for her.

Zhao's attack misfired as Marie placed her pieces wisely and secured the full point after 63 moves.

Yifan Hao could not break the defenses of Elina Danielian, who played the black side of a Caro Kann defense.

Going for a less-played system in the opening, Yifan came under pressure after sacrificing a pawn in the center and had to find ways to complicate matters.

Elina came up with exchange sacrifice in the late middle game and was out of danger soon after thanks to her well advanced passed pawn in the center and Yifan had to give her extra material back to restore parity.

The game was drawn after 45 moves.

In other games of the day, Martha Baquero Fierro of Ecuador put an end to her string of five losses in a row by beating Shen Yang, Maia Chiburdanidze of Georgia proved too for local hopeful Betul Cemre Yildiz while Swede Pia Cramling played out a draw with Zeinab Mamedjarova of Azerbaijan.

Results round 10:

Koneru Humpy (Ind, 7.5) beat Antoaneta  Stefanova (Bul, 5); Zhao Xue (Chn, 7.5) lost to Marie Sebag (Fra, 6); Yifan Hao (Chn, 7.5) drew with Elina Danielian (Arm,7); Martha Baquero Fierro (Ecu, 4.5) beat Shen Yang (Chn, 2); Pia Cramling (Swe, 4.5) drew with Zeinab Mamedjarova (Aze, 2); Betul Cemre Yildiz (Tur, 1.5) lost to Maia Chiburdanidze (Geo, 5).

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