The 24-year-old world No. 12th, who's just making her comeback from a back injury, badly twisted her right ankle during her second round tie against world No. 1 Victoria Azarenka on Thursday night.

　　Scans at hospital in Stuttgart on Friday revealed that Petkovic has torn two ligaments and damaged a third in her right ankle and may need an operation.

　　"I have to start the recovery process all over again," said the quarterfinalist of last season's Australian, French and U.S. Opens. "As a professional athlete, there are always setbacks, but an injury like this is painful."

　　Petkovic, however, may yet be able to play at the London Olympic Games which takes place from July 27-August 12.

　　The Grand Slam tournament at Roland Garros starts in Paris on May 27, while Wimbledon begins on June 25.