Unseeded Thai Tamarine Tanasugarn stunned second seed Jelena Jankovic of Serbia 6-3 6-2 at Wimbledon on Monday to reach her first grand slam quarter-final.

The women's draw has now lost the top three seeds after early exits for world number one Ana Ivanovic and former champion Maria Sharapova.

It was the first time since full seedings were introduced in 1927 that the top three women's seeds failed to reach the last eight, according to Wimbledon statistics.

Tamarine, who turned 31 in May and is the oldest woman left in the draw, screeched with delight and sank to her knees after Jankovic hit a forehand long on the first of three match points.

The world number 60 took full advantage of another erratic display from Jankovic, who appeared to be moving freely despite suffering a knee injury in struggling to overcome third round opponent Caroline Wozniacki on Saturday.

A break in the sixth game was enough for Tamarine to go on and clinch the opening set, and at 2-1 to the Thai in the second both players called for treatment.

Jankovic received attention to her troublesome left knee while Tamarine lay face down on court as a trainer probed an apparent back problem.

The timeouts made little difference to the course of the match and a dejected Jankovic had no answer to the scuttling Thai's consistency from the baseline.

Defeat leaves Jankovic, 23, still waiting to make her grand slam breakthrough. The Serb, who won mixed doubles at Wimbledon last year, has not gone beyond the fourth round in singles and has yet to reach the singles final of a grand slam.