Nadal Retires From US Open Semi-Final

A weary and wounded world number one Rafael Nadal retired from his U.S. Open semi final while trailing Juan Martin Del Potro 7-6(3) 6-2 sending the argentine back to the flushing meadows final for the first time since his 2009 triumph.

Nadal, who had never before retired from a U.S. Open match, showed signs of distress almost from the start as he limped noticeably after a grueling 69 minute opening set.

He called for the trainer during the changeover on serve at 2-1 in the second.

The defending champion had his knee massaged and re-taped and bravely continued through the second set before telling the umpire he was unable to continue.

It was the second time this year that the world number one has retired from a slam as he also quit during his quarter final against Marin Cilic at the Australian open in January.