If we're doing it by letters:
He's notoriously low-key but appears to be very easygoing and relaxed with people. Leaning towards Introvert. He doesn't seem particularly extraverted. Extraverted tennis players would be Andy Roddick, Novak Djokovic, McEnroe, etc.
More S than N. He seems to be very much aware of things around him with great attention to facts, experiences and specifications.
Definitely more F than T. Infamous for his temper as a kid...but obviously, has managed to control it to the point where his on-court demeanour is described as cold and poker-faced.
Probably P. His wife Mirka seems to be the J of the two.
ISFP - the Artist, I'd say.