By Matthew Cronin
SAN DIEGO, California (Reuters) - Russia's Alisa Kleybanova overcame a sluggish start to upset top seeded Serb Jelena Jankovic 7-5 6-2 in the second round of the San Diego Classic on Wednesday.
The powerful Kleybanova fell into a 0-4 hole in the first set before recovering to take down world number two Jankovic, who lacked mobility and accuracy against her taller opponent.
Jankovic injured her left ankle at a tournament in Slovenia two weeks ago and admitted that she had yet to return to full fitness.
"I had some fear moving because I was afraid I would twist it again," Jankovic said. "I'm not confident where I have to move side to side and play an intense match."
"She's always a great runner and (hitting) a winner against someone else isn't always a winner against her," Kleybanova said after improving her record to 3-2 against Jankovic.
"But if I'm playing my best, my ball is fast enough to make winners against her. She was actually moving pretty well today."
Kleybanova was joined in the last eight by second seeded Samantha Stosur of Australia, who recorded a 6-4 6-4 win over American teenager Melanie Oudin.
Two other seeds also advanced as number four Agnieszka Radwanska of Poland thrashed former world number one Dinara Safina 6-1 6-3 and seventh seed Shahar Peer of Israel overcame Yaroslava Shvedova of Kazakhstan 7-5 6-4.
Stosur used a her high-hopping kick serve and big forehand to subdue Oudin, who had the crowd on her side but could not get near her opponent's serve.
The Australian was able to attack Oudin's weak second serve and shortened rallies by frequently charging the net and knocking volleys.
""She runs a lot of balls down and gets a lot back so if you can get give her less time, you have a better chance of winning the points," Stosur said.
The consistent Radwanska skipped her way past Safina, who littered the court with unforced errors.
Three-times grand slam finalist Safina had won just her second match in four months on Tuesday but against Radwanska, the Russian was often wild off the ground.
"I was more consistent and she was making some easy mistakes," said Radwanska, who had lost her previous two meetings against Safina. "The courts are not playing very fast so I was able to mix it up."
(Editing by John O'Brien)