Swiss tennis star Martina Hingis has undergone surgery on her foot at a Zurich hospital in a bid to cure her recurring injury.

"The operation went well and I'm very pleased," said her doctor, Dr Heinz Bühlmann.

Prognosis unknown

However it is too early to tell whether the 90-minute operation fixed the torn and loose ligaments in her left ankle.

"Martina's foot is stabilised but it could take six to eight weeks to heal," Bühlmann said. The former world number one's tendons are still inflamed and so she will be closely monitored.

"If the inflammation persists, the prognosis will not be good," Bühlmann cautioned. The comment seemed to confirm previous reports that the 21-year-old's tennis career could be over.

Hingis's manager, Mario Widmer has been quoted in a Swiss newspaper as saying that speculation about the Swiss player's possible retirement were "not only premature at the present moment but also completely exaggeragted."

Legal battle

Hingis is still involved in a legal case against shoe manufacturers Sergio Tacchini, after she alleged that the company's shoes caused her foot injuries.

Since turning professional in 1994, Hingis has never missed a Grand Slam event. Her absence from the French Open will end a run of 29 straight appearances at the world's top four tennis tournaments.

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