Former world number ones Serena Williams and Lindsay Davenport, both back in action after injury, experienced contrasting fortunes at the Los Angeles Open on Wednesday.

Williams, playing her second tournament in seven months because of a chronic knee problem, booked her place in the third round with a 6-3 6-2 win over fellow American Ashley Harkleroad.

But fourth seed Davenport, sidelined since March because of a back injury, struggled with her serve before losing 6-7 6-4 6-3 to Australian doubles specialist Samantha Stosur.

Top seed Maria Sharapova of Russia, who won her second WTA Tour title of the year at the Acura Classic on Sunday, maintained her superb form with a clinical 6-3 6-1 win over compatriot Anastassia Rodionova in the day's late match.

Williams, champion in Los Angeles in 1999 and 2000, expressed mixed feelings after finishing her second-round match in just over an hour.

"I think it was all right but I was not as strong as I would like," the seven-times grand slam champion told reporters. "I was just a little slow today, a little bit lazy."

Williams had not competed since losing to Russian Vera Zvonareva in the Cincinnati Open semi-finals last month, her first tournament since the Australian Open in January.

She will meet seventh-seeded Daniela Hantuchova in the third round after the Slovakian beat American Lisa Raymond 7-6 6-2.

Davenport, a four-times winner in Los Angeles, was nowhere near her best on a sun-baked afternoon at the Home Depot Centre and was broken three times in the final set.

"I need to learn to react again," the 30-year-old said after serving 10 double-faults and hitting 29 unforced errors. "It stinks, but it is a step forward for me."

In other second-round matches, 15th-seeded Frenchwoman Marion Bartoli beat Jill Craybas of the US 6-2 6-0, German sixth seed Anna-Lena Groenefeld dismantled Japan's Akiko Morigami 6-3 6-2 and Serbian Ana Ivanovic, the 10th seed, scraped past Italian Mara Santangelo 7-6 7-5.