AMELIA ISLAND, Fla. (AP) -- Elena Dementieva took two long strides and lunged for a drop shot, barely reaching the ball to hit a winner and close out the first set Thursday.

Within moments, a trainer was looking at the Russian's left heel. A few hours later, she officially joined the list of injured players at the Bausch & Lomb Championships.

``I went on and tried to forget about it,'' the third-seed Dementieva said after her 6-4, 6-2 victory over countrywoman Elena Likhovtseva.

She worked her way gingerly around the court during the second set, but that simply delayed the inevitable.

After the match, Dementieva was walking on crutches, and went to a hospital to have the heel checked. Doctors diagnosed her with a partial tear of a tendon running down the bottom of her foot. She was listed as questionable for Friday's quarterfinal against sixth-seeded Amelie Mauresmo, a 7-6 (3), 4-6, 6-3 winner over Lisa Raymond.

If the injury is as bad as it looked, it will further ease top-seeded Martina Hingis' road to a title in her first appearance on the green clay at Amelia Island.

Hingis defeated 15th-seeded Henrietta Nagyova 6-1, 6-3 in a hard-hitting, back-and-forth match that was much closer than the score indicated. Hingis pulled ahead 2-0 in the second set but Nagyova tied it at 2 by winning a game that went to five deuces.

``I wouldn't say I got lazy, but maybe a little cocky out there,'' Hingis said. ``I felt very confident. Then, all of the sudden, it was 2-all.''

It took Hingis another 30 minutes to close out the match.

She advanced to play in the quarterfinals against Arantxa Sanchez-Vicario, who defeated ninth-seeded Paola Suarez 6-2, 6-4. Hingis leads the series 15-1.

``I have nothing to lose, so that will help me play my own game,'' Sanchez-Vicario said. ``I'll be aggressive and take chances that you have to to beat the No. 1 player in the world.''

Before the tournament began, Monica Seles and Anna Kournikova pulled out with foot injuries. On Monday, Mary Pierce tweaked her back throwing a medicine ball, and she had to withdraw. Second-seeded Conchita Martinez lost her first match, leaving very few well-known names outside of Hingis.

The top-ranked Swiss star, often viewed as susceptible because she doesn't have the power game of the Williams sisters, Pierce or Dementieva, said that also might be one reason she's not as susceptible to injuries.

``Everyone is in training, but it's just that many people don't know what's the right thing,'' Hingis said. ``They're physically, obviously, in great shape. But tennis is not always just a physical sport.''

After her match, Hingis learned that the man convicted of stalking her, Dubravko Rajcevic, had been sentenced to two years in jail during a hearing in Miami.

``I'm definitely very, very happy that I don't have to think about it anymore,'' she said. ``I went through it and now it's over.''

In a night match, fourth-seeded Amanda Coetzer defeated 13th-seeded Jelena Dokic 6-4, 2-6, 6-3 to spoil Dokic's 18th birthday.

Dokic's father, Damir, was in the stadium for the first time since the WTA banned him after the U.S. Open last year. He was tossed out of both the Open and Wimbledon following confrontations with authorities.

Dokic sat calmly through most of the match, and smoked a cigar during the second set. After match point, he bolted from his seat and was the first person out of the stadium.

Coetzer will advance to play 10th-seeded Meghann Shaughnessy, who defeated Melien Tu 4-6, 7-5, 6-0.