MOSCOW (AP) -- Martina Hingis was stunned by 169th-ranked Nadia Petrova 6-2, 6-2 Monday in the first round of the Kremlin Cup.

It was the first match for Hingis, who turned 22 Monday, since her fourth-round loss to Monica Seles at the U.S. Open. Hingis, formerly ranked No. 1 and a five-time Grand Slam singles champion, had ankle surgery in May and was sidelined three months.

In another upset, French Open champion Albert Costa was eliminated by Nicolas Escude 7-5, 3-6, 6-1. That was the only men's match of the day.

Against Petrova, the fifth-seeded Hingis' serve was broken in the first game and she dropped the final four games of the first set. Hingis wound up losing the match in just 49 minutes.

``I had certain problems with my service today, while Nadia was serving pretty well, preventing me from catching the rhythm of the game,'' Hingis said.

``It was my first indoor tournament after the injury and definitely not my best day.''

Hingis won this tournament in 2000, and was the runner-up last year.

In other first-round action, Tatiana Panova beat Anne Kremer 7-5, 6-3, and two-time champion Magdalena Maleeva defeated Anna Smashnova 6-1, 6-2.

Costa, seeded third, had three set points while serving at 5-3 in the first set. But the 48th-ranked Escude erased those en route to taking four games in a row.

Escude raced to a 5-0 lead in the final set.