As a tennis player you can win and you can lose, and you have to be ready for both. I practised self-control as a kid. But as you get older they both - winning and losing - get easier.

I have no sense of humor about losing

I am happy with being a tennis player and the choice I took when I was 12. But clearly, if I wouldn't have been a tennis player, I would have loved to be a soccer player. But again, I am happy with the choice I made.

Relationships are give-and-take, and when you're a tennis player, you're certainly not giving. You have to be self-absorbed. It has to be about you.

I've stayed calm when I'm winning and I've stayed calm when I've lost. Tennis is a sport where we have a lot of tournaments every week, so you can't celebrate a lot when you have big victories, and you cannot get too down when you're losing, as in a few days you'll be in the next tournament and you'll have to be ready with that.

Federer is the No. 1 in tennis, and if I meet him in the Masters Cup, I'll play a world No. 1. It will be difficult, but I' m very young and have nothing to be afraid of.