The much-anticipated potential quarter-final between the back-from-retirement Belgians dissolved in 52 minutes yesterday at the Australian Open.

That's the time it took for Kim Clijsters to lose, in embarrassing fashion, her third-round match at the season's first Grand Slam tournament.

The 6-0, 6-1 defeat to Nadia Petrova was the worst of Clijsters' career and as one-sided as the score indicated. Clijsters lost the first set in just 18 minutes and won only five points in her first seven games.

Justine Henin, another Belgian who was inspired to return to the tour following a 20-month absence after Clijsters won the US Open, held up her end of the bargain. With some difficulty, she defeated Alisa Kleybanova 3-6, 6-4, 6-2.

"I just didn't give her a chance to get into the match," Petrova said. "I like this kind of Grand Slam feeling."

Clijsters hadn't been on the receiving end of such a lopsided scoreline since losing the French Open final to Henin 6-0, 6-4 in 2003.

"I was completely off. I think tennis-wise, I didn't feel the ball at all," Clijsters said. "On the other hand, she was good, but I made all the mistakes and she really didn't have to do much.

"It's something you don't want to happen too often. It sucks that it has to happen at this stage of this tournament."

Defending champion Rafael Nadal advanced to the fourth round, along with Andy Murray, U.S. Open champion Juan Martin del Potro, Andy Roddick and Fernando Gonzalez.

Nadal, who beat Roger Federer in last year's final, held off Philipp Kohlschreiber of Germany 6-4, 6-2, 2-6, 7-5 in a night match. In the fourth round, Nadal will play Ivo Karlovic, who beat Ivan Ljubicic 6-3, 3-6, 6-3, 7-6 (7). The 6-foot-10 Karlovic holds the tour record for the most aces in a match with 78.

"He's a really difficult opponent because the match is decided in a few points," Nadal said. "So the thing is to concentrate with my serve all the time and try to convert the small opportunities that I can have on the return."