You have to be extreme to be exceptional. I couldn't revel in being number one. I had to get to zero. When my fitness was at its peak, I was intimidating. I made guys cave in. They'd be dejected in the locker room after matches, and I'd go out for a run, as if it wasn't enough. I'd rub it in their faces. I meant to do that.

Tennis is more than just shots. It's about being clutch and beating the people on the other side of the net.

The good news is I have time.

You need to make sure everyone is healthy first and foremost.

America has an interesting global role, don't we? It certainly seems to be changing. Our government right now has a softer hand than we've had in the past, but I still think that we're the global behemoth.

We lose a lot of young athletes because tennis is such a difficult sport. It's not like kicking a soccer ball.

It's really easy to find your friends when you're playing away. You have a close-knit group with you and everyone else is cheering hard for their side. There's more satisfaction coming away with a road victory.