Samantha Stosur spoiled Lindsay Davenport's return from injury on Wednesday, outlasting the former world number one 6-7 (4/7), 6-4, 6-3 to reach the third round of this 600,000-dollar WTA US Open tune-up.
Davenport, seeded fourth, was playing for the first time since March, when she revealed she had been diagnosed with a bulging disk in her lower back.
"It stinks," Davenport said of the defeat. "But it is a step forward for me."
While Davenport can only hope her abbreviated preparations for the US Open will be enough, top-seeded Russian Maria Sharapova continued to display solid form heading into the final Grand Slam of the year.
Sharapova, winner of the title at San Diego on Sunday, opened her Los Angeles campaign with a 6-3, 6-1 victory over compatriot Anastassia Rodionova.
The 106th-ranked qualifier surprised Sharapova with a break of serve in the fifth game of the opening set. But it seemed only to galvanize Sharapova, who lost just three points in the next four games as she closed out the set in 28 minutes.
The world No. 4 then cruised through the second set to book a third-round clash with France's Marion Bartoli.
"She swung freely out there at the beginning of the match. It took a few games to get used to the rhythm and the timing," Sharapova said.
"She played a pretty good game when she broke me. After that I stepped it up. I did what I needed to do."
Davenport was under no illusion that she would find the going easy when she returned to competition with less than four weeks of practice under her belt.
She admitted that she was feeling the strain in he third set, when she dropped her serve three times and double-faulted on match point to hand the win to Stosur, who is better known as half of the top women's doubles team in the world.
"My body started to feel drained as the match went on, which I expected to be the case," Davenport said. "I'm happy at least I felt my body didn't get injured. The back was fine. My arm was just so tired."
Davenport credited Stosur's solid service performance, which included 15 aces, with preventing her from finding any comfort level.
"I certainly served one of my best matches today," Stosur said. "That really got me going. That maybe put a little more pressure on her."
But Stosur acknowledged she could tell that Davenport, a three-time Grand Slam champion, was not at her peak.
"She always hits the ball hard and flat and deep, she still was able to do that," said Stosur, who has won six doubles titles this year with Lisa Raymond, including Roland Garros.
"I don't think she was moving very well today. She threw in some double-faults at bad times...match point...you kind of don't expect it from a player of her level."
Despite the disappointment, Davenport was cautiously optimistic.
"You certainly don't feel your best after you play a shade of what you feel you can play," Davenport said. "But it's a long road back after any injury.
"Hopefully, the next time you see me I'll be much sharper."
Seven-time Grand Slam champion Serena Williams continued her progress back from injury with a 6-3, 6-2 victory over Ashley Harkleroad.
Williams is playing just her third tournament of the year - her second since a six-month injury layoff.
In the third round she'll face seventh-seeded Slovakian Daniela Hantuchova, a 7-6 (7/2), 6-2 winner over Raymond.
Hantuchova dethroned Williams in the third round of the Australian Open in January, and the American didn't play again until three weeks ago, when she reached the semi-finals in Cincinnati.
With her nagging left knee injury behind her, Williams said she was looking forward to the rematch.
"She was the last person I played before I took the layoff, so I'll be ready," Williams said. "I'm a much better player than I was in Australia. I'm much more fit, I'm much more ready. I'm not struggling physically. It's a whole new ballgame."