World No. 22 Peer stirred up a hornets' nest of controversy a year ago when she was refused a visa by the UAE and was unable to compete.

She has been playing this week on a well-secured side court, with the few spectators put thorough airport-style security before taking seats in the well-patrolled stands.

With Peer next facing the winner from defending champion Venus Williams and Russian Anastasia Pavlyuchenkova, the decision on where to stage that match is sure to be an agonizing one.

Peer has quietly worked her way through the week as the first Israeli to play in the ten-year-old women's event, which precedes the well-established men's ATP week dating to 1993.

Li, an Australian Open semifinalist, took treatment on court for her back problem and was unable to go on after 77 minutes.

"At the end of the first set, I was hit a high backhand, and then I heard like 'crack'," said No. 10 Li. "After the first set I called the official and then I tried for two more games.

"But it was feeling worse, so I pulled out. I had a chance to win first set, but she was fighting a lot on the court. I missed a lot today."

The Israeli broke four times against her hampered opponent as she reached a third semi-final of 2010.

The victory over Li was the first for Peer after losses to the Chinese eighth seed at the US Open and Doha in 2008.

"I just played my tennis, I didn't think about bodyguard," said Li. "I just played my tennis, nothing special."