Former US Open champion Juan Martin Del Potro has torn a hip muscle and looks almost certain to miss the French Open, his coaching staff said yesterday.

Del Potro, who won his first grand slam title at the US Open in 2009, pulled out of the Madrid Masters tournament last week due to the injury and the French Open starts in less than two weeks' time.

The 1.98-metre 22-year-old had tests in Buenos Aires on Saturday that showed an eight millimeter tear in a left hip muscle, his staff said in a statement.

"We still don't know how long it will take for Del Potro to return to the circuit but it is most probable that he won't get to play the second Grand Slam of the season, Roland-Garros," they said.

Del Potro was quoted on the statement as saying: "I started rehabilitation today (Monday) and I will do all I can to play in Paris.

"I want to take things calmly without hurrying my return to the circuit."

Del Potro, ranked 31 after winning his ninth title at Estoril on May 1, has been making a comeback this season after missing almost all of last year following wrist surgery.