World No. 4 Argentine tennis star Juan Martin del Potro has fractured his right kneecap, initial medical tests said. "It's a very difficult time... it's a hard blow that leaves me without any strength mentally. It makes it very difficult for me to get back to recovery. I didn't expect it," said Del Potro in a statement.

The Argentine player will continue to rest, as his doctors have instructed on Sunday, until he undergoes new tests that will determine more specifically the extent of the injury, Efe news reported.