Down and out: Seles had treatment on her ankle

Former Australian Open champion Monica Seles was knocked out of this year's event by Klara Koukalova of the Czech Republic.

Qualifier Koukalova, ranked 113 in the world, beat the veteran sixth seed, who has won the title four times, 6-7 (6/8) 7-5 6-3.

It is the first time that the 29-year-old Seles has failed to reach the last eight in Melbourne and is bound to fuel speculation that she may retire this year.

It had looked as if the match would be over very quickly when Seles went over on her ankle in the third game of the opening set.

But after off-court treatment the American was able to continue and she came from a break down to edge the first set tiebreak 8-6.

But the 20-year-old Koukalova fought back in the second set and levelled the match with a cracking forehand return down the line.

Even If I'd have got away with it today, I wouldn't have got away with it the day after tomorrow Monica Seles

As Seles began to tire, the Czech player kept up the pressure and took the decider 6-3 to move into the third round at her first ever Australian Open.

Seles admitted afterwards that she had been hampered by the injury to her ankle.

"It was a struggle, I just tried to fight through the pain but it was too much," she said.

"It was a struggle from the moment I sprained it. I was just a step slower and I couldn't change directions.

"And, even If I'd have got away with it today, I definitely wouldn't have got away with it the day after tomorrow."