Tennis Stars Roger Federer and Lleyton Hewitt Play Tennis On Speedboats

— -- Tennis stars Roger Federer and Lleyton Hewitt played tennis across speedboats in the Sydney Harbor Monday.

Each tennis star had their own boat, with its own driver, and as the boats sped through the harbor the pair tried to volley the ball back and forth to one another.

The video shows the tennis pros struggling to find balance, losing more than a few tennis balls in the harbor and almost hitting one of the speedboat drivers with a ball. But, occasionally the pair managed to find a rhythm and actually hit the same ball back and forth multiple times.

According to 9News, the stunt was performed to promote FAST4, a new tennis format that will be launched Monday night at the Qantas Credit Union Arena in Sydney, Australia.