"If I had won the second game of the second set, the result would have been like the first set," said Petrova, ranked No. 12 in the world. "When she got that key game, she felt like she was back in the match."

At one point, Chakvetadze led 5-0 in the third set, but had to withstand one last charge from Petrova before putting her away for the fifth straight match.

"I started out the match very badly," said Chakvetadze, who has fallen from a career high of No. 5 two years ago to 48th. "I had no chances early. I made mistake after mistake.

"She started playing better because she had nothing to lose. The third set was a disaster. I was lucky I won it."

In another first-round match, Alona Bondarenko defeated wild-card entry Meghann Shaughnessy, 4-6, 6-3, 7-5.

Taylor Dent won his first-round match in the men's tournament, beating Ivan Ljubicic, 6-3, 6-4, to continue his comeback after retiring following two back operations three years ago.

Dent's ATP singles ranking has risen from No. 865 at the start of this season to No. 202 at the start of last week.

The American wild-card entry was ranked a career-high 21st in August 2005, before severe back pain put him on the sidelines, including a six-month stretch in a body cast.

"My goal was to walk down the street, not win tennis matches out there," Dent said. "I'm a huge believer in taking steps as small as I can."

David Ferrer, seeded No. 4 in the men's main draw, withdrew because of a knee injury without playing a match.