Whoever has played tennis knows the court is pretty big and you always have space to put the ball in.

The grass is a very big challenge for me. There are these low bounces and different movements, which is very difficult, especially for my height and weight. When the surfaces change, and I start to play on grass, I start to feel it in the lower back and the lower hamstring.

I do a lot of biking. I need that mileage and the long-distance stuff because tennis demands it. My fitness trainer is always trying to convince me to do an Ironman. I can probably run the marathon, I can make the 112 miles on the bike, but I will never swim for 2.4 miles. I will die after 100 meters.

I can see that the tennis for the fans could be a bit boring, and these days you have these new modern things which you can do, and you have a lot of time, because you just play a match, and practise, and many times in between you can bring many things to the fans.