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

I liked Pat Cash, and I loved Mats Wilander. I went to the Australian Open with my parents, and I used to watch Wilander being cheered on by the Swedish fans, and with his game style being like mine, I drew comparisons with him.

My video game character is a bit better looking than me, actually. I don't think he has to worry about his hair getting messed up.

I think I was as mentally tough as I've ever been. I felt like I handled the situation both on and off the court extremely well. I felt like I needed to.

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.

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.

I don't know. Haven't I always been mature?