The serve and leg drive

“The one commonality in great servers I think is a big knee bend, a big, strong base leg,” Roddick told Tennis Now. “I think people talk about shoulders and live arm a lot – I think that’s probably overstated.

“I think the part that’s understated is if you look at Sampras and Becker and Ivanisevic, just the power and drive they get from their legs.”