CARSON, Calif. -- Maria Sharapova upset No. 14 seed Nadia Petrova, 6-2, 2-6, 7-5 Tuesday night in the first round of the JPMorgan Chase Open.

Chanda Rubin, who won the tournament last year, withdrew due to right shoulder tendinitis. The No. 3 seed said she developed pain in the shoulder while practicing Tuesday and pulled out after seeking medical advice.

"I was advised by the doctor not to play to prevent further injury and avoid surgery,'' Rubin said in a statement issued by the WTA. "I was ready to play, but unfortunately I have to take some time to recover.''

It was the ninth win in the past 11 matches for Sharapova, who advanced to the semifinals at Birmingham, England, and the fourth round at Wimbledon in her most recent tournaments.

She beat Katarina Srebotnik in the first round Monday and now faces a possible matchup with top seed Kim Clijsters, who was to play her first match Wednesday afternoon against Emilie Loit.

"I just battled my way through the third set. In the second set I let a few important points go. In the third set I took control of them,'' said Sharapova, who joined No. 4 seed Ai Sugiyama, No. 6 Magdalena Maleeva, No. 7 Conchita Martinez and No. 11 Silvia Farina Elia in third round.

Sugiyama was a 2-6, 6-3, 6-3 winner over Saori Obata; Martinez beat Tara Snyder, 6-4, 6-3; and Farina Elia took a 7-5, 2-6, 6-4 victory over Shinobu Asagoe. Maleeva beat Elena Likhovtseva, 6-3, 6-3.

Viktoriya Kutuzova, 14, won her debut on the WTA Tour, beating Lina Krasnoroutskaya, 6-4, 6-4. She will face No. 15 seed Alexandra Stevenson in a second round match Wednesday morning.

"I was very happy _ my first tournament, my first match, against a really good player,'' said Kutuzova, who turns 15 in two weeks.

"I was playing the last point and I was dreaming that I would call my mom and she would be very happy,'' she said. "For sure I was dreaming about this win.''

Kutuzova, who is coached by her father, Valeriy, was included in the WTA rankings this week for the first time at No. 451 after playing the required three ITF tournaments.

She said she was "just playing my style'' and trying to hit the ball hard, and speculated that Krasnoroutskaya was nervous at having to play someone five years younger.

Krasnoroutskaya blamed illness, not nerves, and sought medical attention after the match, saying "I didn't have the energy to move.''

In other first-round matches, Barbara Schett beat former champion Amy Frazier 4-6, 6-4, 6-4; Fabiola Zuluaga topped Tina Pisnik 6-1, 6-3; Svetlana Kuznetsova downed Magui Serna 6-3, 7-6 (3); Nicole Pratt beat Maria Sanchez-Lorenzo 7-6 (1), 6-4; Virginia Ruano Pascual eliminated Cara Black 7-5, 6-3; and Paola Suarez defeated Alicia Molik 6-4, 6-4.