ZURICH, Switzerland -- Martina Hingis may have to give up tennis because of joint injuries, her doctor said Wednesday.
Dr. Heinz Buehlmann told a Swiss radio network that Hingis, 21, is suffering severe pain in her feet, left knee and left hip, which had forced her to stop training.
The former top-ranked player was due to have tests Wednesday and Thursday, Buehlmann told Radio 24. She may have inflammation which has led to joint damage and may have to consider ending her career, he said.
"We cannot yet say how sensible it would be for her to continue her career or whether an end to it would be advisable on medical grounds," Buehlmann said.
Results are expected by the end of the week, Buehlmann said.
Hingis' mother, Melanie Molitor, confirmed that her daughter was undergoing tests in Zurich.
She said the damage may have been caused by the shoes that Hingis wore for tennis from the age of 11 until three years ago.
Hingis missed the German Open last week and the Italian Open this week, and Molitor said that it was unlikely her daughter would compete in the French Open, which starts later this month.
Last June, Hingis filed a $40 million lawsuit against Italian sportswear manufacturer Sergio Tacchini, with whom she had a five-year sponsorship deal. She claimed that she had been provided with defective shoes "unsuitable for competition," forcing her to withdraw from several tournaments.
Sergio Tacchini said the claims had been made only so Hingis could avoid paying damages for breaching her contract with the company.