The average serve speed for a professional tennis player is 148 mph. But many players are capable of serving a lot faster. Here's the fastest servers in the ATP tour.
1. John Isner (USA): 157.2 mph
2. Milos Raonic (CAN): 155.3 mph
3. Andy Roddick (USA): 155 mph
4. Roger Federer (SUI): 143 mph
5. Andy Murray (UK): 141 mph
6. Novak Djokovic (SER): 136 mph
7. Rafael Nadal (SPA): 135 mph