He says he has a knee pain since Miami (against A-Rod), he felt it against in Monte-Carlo and at Wimbledon again.
As he wants to win the US Open, he wants to rest his right knee. He had some pain in the previous round too.
He says he didn't want to talk about it at Miami because he didn't want to make some excuses
He rested up his left knee between MC and Rome, it worked, but didn't have some time for his right one.