Rafael Nadal had to go three full sets Monday to reach the Australian Open quarterfinals, ousting 2007 runner-up Fernando Gonzalez 6-3, 6-2, 6-4.
The two previous fourth-round matches in Rod Laver Arena were cut short when players retired with illness or injuries. A third match was over quickly, with Svetlana Kuznetsova's win over Zheng Jie on Hisense Arena lasting five games before the Chinese player retired with an injured left wrist.
Second-seeded Serena Williams lost the first set to Victoria Azarenka but was up a break in the second when her tearful and dizzy Belorussian rival had to quit because of a vomiting virus.
"Honestly, I got worried," Williams said. "She started walking really slow. The last thing she would want to do, to me, would be fall. It was just weird. I was actually really worried."
In the opening match on center court, No. 6 Gilles Simon was leading 6-4, 2-6, 6-1 when his friend and fellow Frenchman Gael Monfils retired with a right wrist problem.
That brought top-ranked Nadal and Gonzalez on earlier than expected to determine who would meet Simon in the next round.
Nadal ran off 12 of the first 13 points and broke Gonzalez twice in the first set en route to his third quarterfinal appearance at Melbourne Park in his last three trips.
The 22-year-old Spaniard went down a break in the third set but rallied to win five straight games and six of the last seven.
Gonzalez, who beat Nadal here in the quarterfinals on his run to the final two years ago, was coming off a difficult third-round win, when he rallied from two sets down to beat Richard Gasquet 12-10 in the fifth.
Matches early Monday were over surprisingly quickly, considering conditions were sunny and mild with temperatures hovering around 75.
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 time-out earlier in the set and left the playing arena. She returned for 1 1/2 games but was unable to continue and was helped from the court soon after by two trainers.
"The doctors didn't want me to keep going, but I wanted to keep trying and see how I do," she said. "But it was probably not a very good idea because it just gave me even more trouble after."
Azarenka was taking the match to Williams, with both women going for winners constantly.
Williams was looking quicker on her feet than in her last two matches, but her first serve was another matter.
Clearly trying to concentrate, she regularly was bouncing the ball 20 times — she once hit 37 — before making her toss.
At 3-5 in the first set, Williams double-faulted for the second time to give Azarenka a set point, then loudly cursed her first serve, earning a warning from the umpire for an audible obscenity and sending a backhand long on the next point.
Things got better for Williams as she saved three break points in her opening serve of the second set in a game that went to deuce five times, then broke Azarenka to pull ahead at 2-1.
Azarenka appeared to become ill after pulling within 3-2 and went off court. Williams took advantage of the time to get her ankles retaped.
Azarenka said she'd been feeling sick all morning.
"I woke up at 6 a.m. and I was throwing up all the morning and just felt weak," she said. "Once I got to the court, I went to see the doctor, I felt a little bit better.
"It's very disappointing for me that I played that well and I couldn't handle a little bit more because it was really close games."
Williams, seeking a 10th Grand Slam singles title, next plays 2004 U.S. Open champion Svetlana Kuznetsova, who advanced when Zheng retired while trailing 4-1 in the first set after tumbling onto her wrist at the end of the third game.
Williams and Kuznetsova are the only major winners still in the women's draw.
The winners of Monday's 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.
Olympic gold medalist Elena Dementieva 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.
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.
She could take the No. 1 ranking by winning the tournament, one of three players who can do that.
"It's a great motivation for everyone," she said.
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.