A players stroke are evolving over time. Andy Roddick is a perfect example of that. Click here to see his serve at age 12, side by side with his serve of 2003.

Andy Roddick; Groundstrokes practice

Andy Roddick; Groundstrokes practice

Andy Roddick; Serve practice

Andy Roddick; Practice

Andy Roddick; Practicing with Jimmy Connors