Juan Martin Del Potro has suffered an eight-millimeter tear in his left rectus muscle, reports La Nacion. Del Potro suffered the tear at last week's tournament in Madrid. The left rectus muscle is part of the quadriceps and is close to the hip. Upon leaving Spain to go back to Argentina for medical tests, the 2009 U.S. Open champion had thought he had suffered a hip injury and after the La Nacion report came out, Del Potro tweeted that he had a tear in his hip, but the official report is said to say it's actually in his left rectus. Del Potro just returned to full time play at the start of this year after missing almost all of 2010 due to wrist surgery, and he is considered doubtful for Roland Garros. He will hold a press conference on Wednesday.—Matthew Cronin