Buenos Aires - Juan Martin Del Potro could miss the French Open after medical tests showed that the Argentine had suffered an eight-centimetre tear in a hip muscle which forced him to withdraw last week before a match against Rafael Nadal in Madrid.
The 22-year-old 2009 US Open champion, who missed much of 2010 as he recovered from wrist surgery, believes he suffered his latest problem during a semi-final at Estoril, Portugal, an event which he won less than a fortnight ago.
He flew home to Buenos Aires for tests, with doctors still unsure if he can play in Paris where the clay court Grand Slam starts a week from Sunday.
"I started rehab today (Monday) and will do everything possible to play in Paris," Del Potro said in a statement, "I want to do things calmly without hurrying my return the circuit."
Estoril was the second title of the comeback season for Del Potro, who also took the trophy at Delray Beach, Florida in February.
Del Potro reached the French Open semi-finals in 2009, his last appearance there.