Federer concerned for injured Nadal

Roger Federer says he’s concerned about the health of his longtime rival, Rafael Nadal, who hasn't played since Wimbledon due to a knee injury.

"I was going to write him and check on him because I can't believe he's been out that long," Federer told reporters in Cincinnati. "I thought the Olympics, okay, that's fine. That's a personal choice. I thought for sure we would see him in Toronto, but now he missed Toronto and Cincinnati.  It's very surprising, because it was nothing that we heard of prior to the injury.  He played so well on clay, and then actually seemed fine at Wimbledon. He had more time by losing earlier at Wimbledon.  So it came as big surprise now, these two pull outs for me.  Even the Olympics, too.  So I'm sad for him.  I hope he'll be back for the [U.S.] Open."