Maria Sharapova, from Russia, reacts after losing a game to compatriot Anna Chakvetadze, during the first set of their third-round match of JP Morgan Chase Open, Thursday, Aug. 11, 2005, in Carson, Calif. (AP)

Maria Sharapova survived an injury and another challenge from a fellow Russian, defeating Anna Chakvetadze 4-6, 6-4, 7-5 Thursday in a third-round match at the JPMorgan Chase Open.

Playing her first tournament since losing in the semifinals at Wimbledon, Sharapova made numerous errors that allowed the 34th-ranked Chakvetadze to prolong her upset bid.

Sharapova said she played in pain from an inflamed right pectoral muscle that affected her ability to serve hard and pound forehands.

"It wasn't me out there today," she said. "I'm serving 93 miles per hour and not hitting my forehand. With that, it's tough to come out against a player that has nothing to lose."

Sharapova said she first injured the muscle in October in Zurich, playing with heavier balls.

"Since then, it's been an on and off problem for me," she said. "I don't think the pain is going to go away with me trying to play and hit as hard as I can."

She had an MRI on Wednesday that showed the muscle is inflamed, not torn. She taped it for the match, and planned to seek treatment Thursday night.

Sharapova is trying to take over the No. 1 world ranking from Lindsay Davenport, the defending champion who is out with a back injury. Sharapova trails Davenport by 23 points and could become the first Russian to be No. 1 depending on her results this week.  

(Agencies)