Already eliminated, ailing Ivanovic pulls out of Sony Ericsson

DOHA, Qatar -- Ana Ivanovic withdrew from her last round-robin match at the WTA Tour's season-ending Sony Ericsson Championships on Friday because of a virus.

The French Open champion had no chance of advancing to the semifinals after losing her first two matches in the group stage.

Svetlana Kuznetsova, her scheduled opponent, had also lost two matches and had no chance of advancing to the elimination rounds.

"It's obviously very hard for me," said Ivanovic, who turned 21 on Thursday. "Yesterday I didn't feel good and today, even worse."

Ivanovic picked up $100,000 despite her disappointing results. Kuznetsova won $200,000.

The tournament features eight players divided into two groups, with the top two in each group advancing to the elimination stage.