MOSCOW -- Top seed Martina Hingis advanced to the Kremlin Cup quarterfinals Wednesday with a 7-5, 6-2 win over Czech qualifier Sandra Kleinova, before revealing doubles partner Anna Kournikova may have injured herself again.

Hingis, the defending champion, fell behind early in the match as she struggled with her usually reliable all-court game but, after drawing level at 5-5, the Swiss world No. 1 finally broke 135th-ranked Kleinova in the 12th game to take the set.

In the second set Hingis found her range, racing to a 5-1 lead before clinching the match in 63 minutes.

"She already played four matches here, in the first round and qualifiers, while it was my first match here so it took me a while to get going," said Hingis.

"Besides I have never played her before and I didn't expect her to play that good.

"In the first set, she was just kept hitting down the lines and by the time I realized it, she was able to score a lot of points," she added. "I was fortunate my first serve was working and it got me out of trouble in the first set."

On Tuesday, Kournikova lost 6-2, 1-6, 6-2 to 17-year-old compatriot Galina Fokina, her third straight loss after trying to come back from a foot injury.

"Anna is still struggling with her injury," Hingis said. "I don't know if I should say this, but she went to hospital after yesterday's match. She needed treatment on her foot."

Hingis said she would continue playing doubles with Kournikova.

"We really enjoy playing doubles together, and provided Anna is healthy enough to play, we will continue our partnership this year and the next."

Fourth-seeded Nathalie Tauziat of France had a rough time, losing to Francesca Schiavone of Italy 4-6, 7-5, 7-5 in the second round.

The 34-year-old Tauziat, the oldest woman on the tour, won this event in 1999.

In other first round matches, Austria's Barbara Schett beat Russian Elena Likhovtseva, 6-1, 6-4, while seventh seed Magdalena Maleeva of Bulgaria eliminated Germany's Anke Huber, 6-3, 7-5.

On the men's side, former U.S. Open champion Marat Safin overpowered Max Mirnyi 5-7, 6-4, 6-4 in a battle of two big-hitters in the first round.

After losing the opening set, Safin broke his opponent to love in the fifth game of the second set when Mirnyi's serve suddenly deserted him.

In that game, the lanky Belarussian missed all his first serves, double-faulting twice to hand his opponent a 3-2 lead from which he never recovered.

"I was really upset with Max's attitude on the court," Safin said. "We know each other a long time and have even played together in doubles, but tonight he twice hit a lucky shot and never apologised for that.

"Come on, if you hit a ball with a frame and win a point, be a real sportsman and say something or raise your hand," lamented the Russian second seed. "He never did that and it got me angry. I was going to teach him a lesson in sportsmanship."

Safin scored a decisive break in the ninth game of the final set with a perfect backhand lob for a 5-4 lead, then held comfortably in the next game to clinch victory in 90 minutes.

Fourth-seeded Tommy Haas of Germany downed qualifier Bob Brayan of the United States 6-1, 6-4; seventh-seeded Canas Guillermo of Argentina routed Andreas Vinciguerra of Sweden 6-0, 6-1; and David Nalbandian of Argentina beat Anthony Dupuis of France 7-5, 6-4.

Switzerland's Marc Rosset, twice Kremlin Cup champion in 1992 and 1993, defeated Yugoslav Nenad Zimonjic 6-4, 6-7 (4), 7-6 (11). The final set lasted for over an hour.

Information from The Associated Press was used in this report.