PARIS - If Caroline Wozniacki truly was torn up inside about her latest loss at a Grand Slam tournament, she certainly hid it well. Wozniacki smiled and shrugged while deflecting questions about being No. 1 in the rankings despite never having won a major title. Her wait for a breakthrough was extended Friday, when she was beaten 6-1, 6-3 by 28th-seeded Daniela Hantuchova of Slovakia in the third round of the French Open.

After the match, Wozniacki was consoled by her father. She said he told her: "The world still goes on, and we still have the next tournament next week. There is nothing you can do about it now, so just don't beat yourself up too much."

Wozniacki's early exit came a day after No. 2 Kim Clijsters was eliminated by 114th-ranked Arantxa Rus, marking the first time that the top two seeded women failed to make the round of 16 at any Grand Slam tournament in the Open era, which began in 1968. It never had happened at the French Open since it began admitting foreign entrants in 1925.

Add that to the absences of the Williams sisters, who are sidelined by health issues, and there is a real lack of star power in Paris now.

"Kim had a tough loss yesterday; I had a tough loss today. That's what happens," said Wozniacki, a Dane who reached No. 1 in October and has been there every week but one since then. "Since we're No. 1 and 2, it means that we must be doing something right. It's just unfortunate to lose in a Grand Slam, but that's what happens."

Hantuchova explained the surprises this way: "It just shows how strong women's tennis is at the moment. It's very open."

As if to prove that point, another French Open title contender, 2010 runner-up and 2009 semifinalist Sam Stosur of Australia, was beaten 6-4, 1-6, 6-3 by 51st-ranked Gisela Dulko of Argentina. But defending champion Francesca Schiavone of Italy advanced when her opponent, No. 29 Peng Shuai of China, stopped playing because she has a cold and couldn't breathe properly.

The most anticipated matchup of the day did not begin until early evening - and did not finish Friday. Two-time Australian Open champion Novak Djokovic, who is on a 41-match winning streak, was tied at a set apiece with 2009 U.S. Open champion Juan Martin del Potro when play was suspended at 9:15 p.m. because of darkness.

The second-seeded Djokovic won the first set 6-3, but No. 25 del Potro took the second by the same score. Right after del Potro held serve to even the match, the chair umpire announced play would stop for the day; there are no artificial lights on the courts at Roland Garros.

Earlier, 16-time Grand Slam champion Roger Federer saved the only break point he faced in a 6-1, 6-4, 6-3 victory over No. 29 Janko Tipsarevic of Serbia.

"I'm at peace with my game right now. I'm physically fine. I think I had a good preparation, so there's no reason to get nervous," said Federer, who hasn't dropped a set heading into his next match, against his 2008 Beijing Olympics doubles partner Stan Wawrinka. "I'm still in the tournament. It's always nice to advance in the draw so well, so quickly."