Oh, I get pretty fired up on the court. I try to play with a lot of emotion, especially when I'm playing in front of a large crowd. I want to go out and do my best, and to do that, I have to play with the most energy possible.

I'm fortunate: I can play as long as I want to play. There's no coach or trainer who is going to say to me that I'm dropped or sacked, it's time to move on. I can play as long as I want to play.

I was lucky enough to win the Davis Cup in my first year in 1999. I won my first slam at the U.S. Open in 2001 and became world No. 1 later that year. By the age of 20, I'd done it all.

I'm one injury away from hanging up the racket at any time.

There are people who love you and people who hate you, but for me, more so, people only think they know me by how I act or perform on a tennis court.

Even when I was No. 1 in the world, I was taking it one match at a time. I never was a player to look too far ahead, the way draws can pan out.

When I go out to play, I still believe I'm as good as anyone out there. I don't have to prove anyone wrong. I know what I've done and how well I can play.