Defending champion Ana Ivanovic of Serbia set up a semifinal against Nadia Petrova of Russia after winning her opening match at the Tournament of Champions on Thursday.
Ivanovic beat fourth-seeded Roberta Vinci of Italy 6-3, 6-3. Earlier, Petrova knocked out second-seeded Peng Shuai of China 6-4, 6-3.
Both winning players needed treatment as they embarked on the last tournament on the WTA calendar. Ivanovic had a foot problem, while Petrova's neck was hurting.
''It was a bit sore, but actually when I was moving it was feeling better,'' Ivanovic said. ''Every time I would sit and then stand up from the bench, that's when it was the sorest.''
Ivanovic made a fast start, jumping out to a 4-0 lead, and though Vinci managed to get back to 4-2, the Serbian put away the first set with a powerful forehand.
The former French Open champion broke three times in the second set to claim victory in 1 hour, 10 minutes.
Ivanovic was given one of two wil...