In the only match involving a seeded player, Petrova prevailed in 45 minutes, taking advantage of an error-prone Hingis, who turned 22 years old Monday.
The Moscow native is playing in only her third event after suffering a left foot injury in January. She started the year with a semifinal effort at Gold Coast, but was forced to retire with a pectoralis strain.
Hingis also is on the comeback trail after undergoing left ankle surgery in May. This is her worst performance since her return. The former world No. 1 reached the quarterfinals in three events this summer before a fourth-round effort at the U.S. Open.
"I have missed out on so much of the season that really today I was finding the game I need to play, (but) it is difficult to get into a rhythm playing Nadia because of her serve," said Hingis, who won here two years ago. "Nadia plays very well and she serves well. It was a difficult match and I was unlucky to lose on my birthday."
Tatiana Panova also advanced before her hometown fans, posting a 7-5, 6-3 victory over Anne Kremer of Luxembourg. Bulgaria's Magdalena Maleeva, two-time winner here, thrashed Israel's Anna Smashnova, 6-1, 6-2.
In the only men's match, Nicolas Escude of France downed third seed and French Open champion Albert Costa of Spain, 7-5, 3-6, 6-1.
Russians Marat Safin and Yevgeny Kafelnikov are seeded first and second, respectively. Safin was booed by the fans here last year during a second-round loss. The Moscow native said at the time he would not play the event again, but is back to try to win his first title of the year. He was runner-up at the Australian Open in January and reached the semifinals at the French Open.
Venus Williams of the United States headlines the women's draw, playing her first event since losing her third straight Grand Slam final to younger sister Serena at the U.S. Open. She is second to her sibling for the WTA Tour lead in titles with seven.
Fellow American Jennifer Capriati was seeded second but withdrew Sunday due to illness. She is suffering from a sore throat and fever.
Lindsay Davenport of the United States filled Capriati's spot in the draw, while Amelie Mauresmo of France took over the fourth seed. Williams, Davenport, Mauresmo and third seed and defending champion Jelena Dokic of Yugoslavia received first-round byes.