Amelie Mauresmo withdrew before her Australian Open quarterfinal match against Fabiola Zuluaga because of a torn back muscle.
The fourth-seeded Mauresmo, injured in the fourth round while stretching for a backhand volley against Alicia Molik, hit for about 10 minutes on center court with coach Loic Courteau, then buried her face in a towel and began to weep.
"I didn't feel very good yesterday," Mauresmo said. "I wanted to try this morning and have a little hit and see how I felt. I have pain. I have to withdraw from this tournament.
"When I hit some shots, I can feel strong pain. The other thing is it could get worse if I play. The best thing to do is to rest."
Courteau said the 27-year-old French player was okay at first, but she began experiencing pain as the warmup intensified.
"As soon as she went up to the net to volley, it was like a knife thrust in her back," Courteau said.
He earlier said a medical scan had shown a slight muscle tear and that no chance would be taken of aggravating the injury.
Mauresmo was seeking her first Grand Slam title. One of the strongest players on the women's circuit, she has been plagued by injuries throughout her career.
Mauresmo, the runner-up in 1999, was dominant in her first three matches, dropping only six games, but tweaked her back in the first set in a 7-5, 7-5 fourth-round victory over Molik.
The 32nd-seeded Zuluaga is the first Colombian woman to make the semifinals of a Grand Slam event.
Ex-Gator Lisa Raymond's opponent in the quarterfinals is No. 22 Patty Schnyder. No. 25 Raymond is 0-4 against her.
Not Australians' day
The fireworks lit up the sky in the middle of the match. It was not the good omen Lleyton Hewitt or his nation would have hoped for on Australia Day.
Hewitt and Mark Philippoussis, fan favorites in November for winning the Davis Cup, lost while a celebration of the country's national holiday crackled nearby.
Rattled by a foot fault, Hewitt was beaten by Wimbledon champion Roger Federer 3-6, 6-3, 6-0, 6-4 in the fourth round. Philippoussis was eliminated 6-2, 6-2, 6-4 by Morocco's Hicham Arazi, sending the last two Aussies from the tournament.
"It's obviously disappointing when you hit an ace and get a foot fault called," said Hewitt, a two-time major winner once ranked No. 1. "I still wouldn't have won the match. I ran into a guy who was too good for me tonight."
Hewitt has been intent on winning the Australian Open but has never reached the quarterfinals of his home championship.
No Australian has won the title since Mark Edmondson in 1976.
"We always have good matches, but he didn't play his best tennis today," Arazi said. "It was one of my best matches."
Federer won nine of 10 games after Hewitt became unsettled by a foot fault that caused him to drop serve in the sixth game of the second set.
Federer, seeded second, punctuated his win with an overhead winner on his third match point.
"Maybe I got a little lucky with that foot-fault call, but I still felt like I started to play better and better," Federer said. "I was playing much more aggressive."
Federer next faces No. 8 David Nalbandian, who beat Guillermo Canas 6-4, 6-2, 6-1 in an all-Argentine match.
Juan Carlos Ferrero twice needed treatment on his upper left leg in a 6-4, 3-6, 6-3, 6-2 victory over Romania's Andrei Pavel. The Spaniard does not expect the injury to trouble him much.
U.S. Davis Cup foe set
Stefan Koubek and Jurgen Melzer were picked for Austria's Davis Cup team, which will play the United States in the first round next month. Julian Knowle and Alexander Peya also were on the roster selected by captain Gunter Bresnik. U.S. captain Patrick McEnroe will announce his team today. U.S. Open champion Andy Roddick is expected to lead the squad. The best-of-five series is Feb. 6-8 in Uncasville, Conn.