The world No. 3 often leans into his forehand, integrating supreme racket head acceleration and stable head and body control to push his opponents into a defensive position.

Instead of my usual big windup, she showed me how to loop my forehand back and down, swing across my body and catch my racket with my left hand. The setup also has changed.

Gary Zaretsky, 69, is another regular on the tennis court. He was very reluctant to try the racket at first, doubting it would make such an improvement. He gave it a try.

7. From an almost-seated position, Djokovic follows through with enormous force. It takes remarkable strength and conditioning to go from full speed to a full stop this quickly.

The racquet has come down sharply from its highest position, and he’s making contact almost where you would expect to hit a volley or a slice approach, with his racquet head just slightly above ...