You cannot risk your shot becoming predictable. At all times, the opponent must be guessing what is coming next. "It's important to set yourself up so that you have multiple options. That's when you are most dangerous for your opponent. Don't always hit in the same spot. What you want to do early in the match is to show your opponent that you can hit all the shots so that when it's important in the match, he doesn't know where it's going to go. I can hit the slice, the topspin and the flat backhand. I try to mix it up as much as I can. But, at the same time, I also need to be able to make enough in a row just for consistency and also for my confidence."
-- Roger Federer
A Graphic Biography of the Genius
of Roger Federer, by Marc Hodgkinson
(London: Arum Press 2016), Page 59.]