Serena, Ivanovic withdraw from WTA Championships

By Barry Wood

DOHA (Reuters) - Serena Williams and Ana Ivanovic withdrew from the WTA Championships on Friday.

U.S. Open champion Williams, who also pulled out of the tournament in 2007 after playing just one set, blamed a sore stomach muscle.

French Open champion Ivanovic, who is suffering from a virus and after losing her first two matches could not qualify for the semi-finals, defaulted her final match against Svetlana Kuznetsova.

After beating Dinara Safina and losing to sister Venus, Williams needed to defeat Olympic gold medalist Elena Dementieva on Friday to qualify for the semi-finals.

Now it will be Dementieva who joins Venus Williams as a qualifier from the maroon group, while Jelena Jankovic and Vera Zvonareva had already qualified from the white group.

Although Serena was able to win only one game during the last two sets of her defeat by Venus on Thursday, she claimed that she only felt the problem develop after she returned to her hotel.

"I had zero pain last night, like zero pain," Williams told reporters.

"I felt like I didn't serve well, I had a lot of double faults. Looking back, I think maybe that's why I was doing it, because I didn't feel it at the time. I think I might have been overcompensating.

"But the moment I got home, I did feel pain last night. But in the match I didn't feel pain at all. When I woke up, I was still in pain just getting out of bed. I've had this before, so once I felt the pain I was like red flags."

Ivanovic had received medical attention for dizziness in both of her matches this week and she revealed that, if anything, her virus infection had become worse.

"The other night was a very intensive and long match and I started to feel actually worse," said Ivanovic. "So, yesterday, I didn't feel good and today even worse.

"I tried to hit actually yesterday. I was on the court for about ten minutes, and as long as I didn't move it was okay. But if I try to hit a little bit harder or to move on the side, it was impossible to do."

Spectators were not left without matches, as Williams was replaced by Russian Nadia Petrova and Poland's Agnieszka Radwanska replaced Ivanovic for Friday's line-up.

(Editing by Miles Evans)