LONDON, Nov. 22 (Xinhua) -- French top seed Jo-Wilfried Tsonga outplayed American Mardy Fish in straight sets on Tuesday to grab his first win at this year's ATP World Tour Finals.

The world No. 6 Frenchman squandered his chances in his last serve in the first set while he led 6-5, but managed to edge Fish with a 7-4 tiebreak.

The 26-year-old Frenchman then dominated the second set, completing it 6-1 to defeat the world No. 8 Fish.

In the first round match last Sunday, Tsonga lost to Swiss master Roger Federer before the season finale debutant Fish bowed to world No. 2 Rafael Nadal.