2009 champ del Potro out of US Open because of right knee
WHITE PLAINS, N.Y. (AP) - Juan Martin del Potro, the 2009 champion, has withdrawn from the U.S. Open because he is still recovering from surgery on his right knee.
The 12th-ranked del Potro fractured his kneecap for the second time in less than a year while playing at grass-court tournament ...