I dont have good luck in the match points.

Some people get very confused about my game. They think it's better if the court is slow, because I have a good defence. But the faster it is, the better for me. My spin is more painful for my opponents, my aggressive game works better.

I do notice that I am tired.

I have no sense of humor about losing

For sure, with golf it's not a physically demanding sport like tennis. That's what makes tennis great - you combine both things. It's a very mental sport and at the same time can be dramatically physical. But I do admire the mentality of sport more than the physicality because physical performance is much easier to practice than mental performance.

I am decidedly unfriendly during a golf game, from the first hole to the last.

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.