The secret of the Juan Martin Del Potro serve

[captainspirou]

There's no secret. He's friggin tall!

[popeye135]

This is more a Karlovic, Ivanisevic, serve style than Juan Matin Del Potro's

[AndresRoddick1]

Lead with your hip and move your body into the shot!!!!

[KevinpeaseAAA]

Okay, I'll give it a try and post it. Thanks for tuning in.

[Hamiltoncheater]

you could show use secret of Karlovic serve better!