SYDNEY, Australia (AP) _ Jennifer Capriati struggled with her serve and a sore leg Wednesday at the Adidas International and lost her opening match to fellow American Alexandra Stevenson.
Capriati, seeded first and preparing to open the defense of her first Grand Slam tournament title next week at the Australian Open, was defeated 7-6 (5), 3-6, 6-4.
``I think I just take it as a learning experience,'' the 25-year-old Capriati said. ``I didn't play that bad and I've got to give a lot of credit to Alexandra, who played really well. But I'm not going to let it get my confidence down.''
The 21-year-old Stevenson advanced to the quarterfinals in Sydney despite wasting two match points. She reached the semifinals at Wimbledon as a qualifier in 1999.
``She is No. 2. I have never beaten anyone in the top five, so it is my best win to date,'' said Stevenson, who last year improved her ranking from No. 112 to No. 57. ``I decided that this was my chance and I was sick of losing. I have done a lot of losing in the last two years, so I am going to make up for the losing and start winning again.''
In a night match, No. 4 seed Serena Williams beat No. 6 Amelie Mauresmo 6-4, 7-6 (6) to reach the semifinals.
Williams produced two big serves in the second set tiebreaker to seal the match after Mauresmo held a set point and was on the verge of equalizing.
``When I really need it, I can pull it out,'' Williams said. ``It's nearly impossible to beat (Mauresmo) on this court, so I either had to show up and play well or go home.''
Williams served nine aces against two, produced 32 winners to 15 and converted both her break point chances, while Mauresmo succeeded with one from eight.
Capriati, who had a first-round bye, left the court for 10 minutes after losing the first game of the third set to get treatment for an injured hip flexor in her right leg.
Then, her game gave her trouble.
Trailing 5-4 in the decisive set but serving, Capriati led 40-0 before a series of errors brought the game to deuce.
Capriati's double fault gave Stevenson a match point, which she threw away with an errant groundstroke. But another double fault followed, then Capriati hit a backhand wide to end it.
The defending Australian and French Open champion said she'd injured her left hip flexor last week in Hong Kong and this time the injury was on the right side.
``I don't think it really made too much difference _ now it hurts, but on the court it was fine,'' Capriati said. ``I don't know what I can say about my game though. I didn't play aggressive enough. I didn't play my game and I was letting her dictate a lot.''
Stevenson wasted another match point while serving at 5-3, wiping it out with a double fault, then putting a forehand wide. But she decided to keep faith in her power game, and it paid off.
Third-seeded Kim Clijsters, who lost to Capriati in the 2001 French Open final, rallied from a set and service break down to beat Italy's Silvia Farina Elia 6-7 (4), 6-4, 6-1.
That set up a quarterfinal between Clijsters and fellow Belgian Justine Henin, who eliminated Conchita Martinez 6-0, 6-3.
In other women's matches, seventh-seeded Sandrine Testud defeated Henrieta Nagyova 6-1, 6-2 in 59 minutes to move into a quarterfinal against defending champion Martina Hingis, while Meghann Shaughnessy had a 6-4, 6-1 win over Daniela Hantuchova.
On the men's side, Paradorn Srichaphan of Thailand _ who ousted top-seeded Sebastien Grosjean in the first round _ lost to Max Mirnyi of Belarus 6-2, 6-3. Mirnyi's quarterfinal opponent will be Julien Boutter, who beat Rainer Schuettler 6-4, 7-6 (3).
Other second-round action included former No. 1 Marcelo Rios eliminating Andrei Pavel 6-1, 6-4, Nicolas Escude beating fourth-seeded Guillermo Canas 6-4, 6-1, and Lee Hyung-taik defeating Karol Kucera 6-2, 6-1.
American Andy Roddick, the No. 3 seed, set up a quarterfinal against Lee with a 6-0, 6-4 victory over Bohdan Ulihrach.