MELBOURNE, Australia — Andy Murray wasn't the only one feeling pain Monday at the Australian Open.

While Murray's anguish was mostly psychological — the fourth-seeded Scot was ousted by Spain's Fernando Verdasco 2-6, 6-1, 1-6, 6-3, 6-4 — three other players had to quit mid-match with injuries or illness, paving the way for Serena Williams, Gilles Simon and Svetlana Kuznetsova to reach the quarterfinals.

Top-ranked Rafael Nadal, meanwhile, left 2007 runner-up Fernando Gonzalez feeling out of sorts with another dominating performance in a 6-3, 6-2, 6-4 win. He has yet to drop a set and next faces the sixth-seeded Simon, who advanced when fellow Frenchman Gael Monfils retired with a wrist injury.

"I am playing well, but you never know if it's going to be enough," said Nadal, who had 33 winners and just 11 unforced errors.

Verdasco will meet fifth-seeded Jo-Wilfried Tsonga of France, who beat No. 9 James Blake 6-4, 6-4, 7-6 (3), leaving No. 7 Andy Roddick as the only American in the men's draw. Tsonga was runner-up last year to Novak Djokovic, while Blake has failed to get past the quarterfinals of a Grand Slam in 28 appearances.

Tsonga was unhappy with a delay caused by Australia Day fireworks. Blake broke him right after they resumed play, but Tsonga rallied and raced through the tiebreaker.

He said he feels he's improved from last year.

"It's different because I have more experience now," Tsonga said. "I hope I will make the results better."

Williams was the biggest beneficiary of the wave of retirements. She lost the first set to 13th-seeded Victoria Azarenka of Belarus and was so frustrated with her first serve that she cursed it, earning a warning for a verbal obscenity. The 19-year-old Azarenka, who woke up sick, had to quit in the second set.

Williams, seeking a 10th Grand Slam singles title, next plays 2004 U.S. Open champion Kuznetsova, who advanced when Zheng Jie of China retired at 4-1 in the first set. They are the only major winners still in the women's draw.

No. 22 Zheng, hoping for victory on Chinese New Year, injured her left wrist when she tumbled after the third game. She had treatment immediately but retired two games later and will go for X-rays Tuesday.

Murray said he, too, hasn't been feeling well the last few days, though he refused to use it as an excuse.

"I don't feel that was the reason why I lost," Murray said. "I definitely did have my chances, and he played too well. I'm disappointed that I lost. But I'll try and learn from it. It's not a disaster. I'm still playing well. I lost to a good player in a very close match. I'll have more chances to win Grand Slams."

Murray saved two match points after falling behind 40-0 in the last game but wasn't able to fend off a third, dumping a backhand into the net.

Murray, who lost in the U.S. Open final last year to Roger Federer, was attempting to become the first British man since 1936 to win a Grand Slam singles title.

Verdasco saved two break points in the pivotal sixth game of the fifth set against Murray, firing aces when he needed them and forcing errors from the other side. He broke Murray in the subsequent game.

"The consistency of his first serve was pretty awesome for the last two, three sets," Murray said.

Verdasco was a key player in Spain's Davis Cup final triumph in Argentina, and he said he was able to draw on the experience.

"I think that Davis Cup final made me much stronger mentally," Verdasco said. "And this preseason, I was working really hard. So today, I was really believing in myself, that I can win the match."