MELBOURNE, Australia — Top-ranked Rafael Nadal reached the quarterfinals of the Australian Open with a 6-3, 6-2, 6-4 win over 2007 runner-up Fernando Gonzalez of Chile on Monday.

MELBOURNE, Australia — Top-ranked Rafael Nadal reached the quarterfinals of the Australian Open with a 6-3, 6-2, 6-4 win over 2007 runner-up Fernando Gonzalez of Chile on Monday.

The 22-year-old Spaniard went down a break in the third set Monday but rallied to win five straight games.

Gonzalez, who beat Nadal here in the quarterfinals en route to the final two years ago, had a difficult third-round win. He had to come back from two sets down to beat Richard Gasquet of France 12-10 in the fifth.

Nadal, the reigning French Open and Wimbledon champion, is bidding to reach his first Australian Open final. He next plays No. 6 Gilles Simon.

Serena Williams also reached the quarterfinals when a tearful and dizzy Victoria Azarenka had to retire in the second set due to sickness.

The 19-year-old from Belarus was one of three players who had to withdraw from fourth-round matches on a sunny but mild day in Melbourne, with temperatures hovering around 75 degrees.

The second-seeded Williams was up a service break at 4-2 in the second set after No. 13 Azarenka had won the first set 6-3.

Azarenka, serving at 30-30, wobbled back into the shade at the rear of the court, holding her face and choking back tears as she tried to regather herself.

She had needed a medical timeout earlier in the set and left the playing arena. She returned for 11/2 games but was unable to continue and was helped from the court soon after by two trainers.

Officials said Azarenka was suffering from dizziness and an "undisclosed illness.

Williams, seeking a 10th Grand Slam singles title, next plays 2004 U.S. Open champion Svetlana Kuznetsova, who advanced when Zheng Zie of China retired at 4-1 in the first set.

No. 22 Zheng injured her left wrist when she tumbled after the third game. She had treatment immediately but retired two games later.

The all-French men's match between Simon and his longtime friend Gael Monfils lasted only three sets.

No. 6 Simon, who was leading 6-4, 2-6, 6-1 when No. 12 Monfils withdrew with a right wrist problem, reached the quarterfinals at a major for the first time.

The winners of the two completed women's matches meet in the quarterfinals.

Carla Suarez Navarro, the 20-year-old Spaniard who had an upset win over seven-time Grand Slam winner Venus Williams in the second round, beat No. 21 Anabel Medina Garrigues 6-3, 6-2.

She next plays Olympic gold medalist Elena Dementieva, the No. 4 seed from Russia who made the quarterfinals for the first time in 11 years at Melbourne Park with a 6-2, 6-2 win over Slovakia's Dominika Cibulkova.

Serena Williams, who has won the Australian title in 2003, 2005 and 2007, and Kuznetsova are the only major winners still in the women's draw.

Suarez Navarro is into the quarterfinals in her first trip to the Australian Open and second time overall, after reaching that round as a qualifier in the French Open.

The fourth-seeded Dementieva, who reached the finals at the French and U.S. Opens in 2004 but has not been to a Grand Slam championship match since, extended her winning streak to 14 matches. She won two titles in tuneup events.

The top eight seeds in the men's draw made it to the fourth round here for the first time since 1970.

No. 4 Andy Murray and No. 5 Jo-Wilfried Tsonga were in action later Monday. If the top eight reach the quarters, it will be a first in a Grand Slam in the Open era.

Simon secured his place quickly Monday. No. 2 Roger Federer, No. 3 Novak Djokovic, No. 7 Andy Roddick and No. 8 Juan Martin del Potro all made it through on Sunday.