Roger Federer, Rafa Nadal and other top tennis players hammed it up in exhibition matches on the eve of the Australian Open to raise money for victims of the country's devastating floods on Sunday.

The men's titans shelved their fierce rivalry to play a few farcical points before teaming up in doubles against Belgium's Kim Clijsters and local hope Sam Stosur in front of 15,000 spectators at a packed Rod Laver Arena.

At least 18 people have been killed in Stosur's home state of Queensland, where floods spanning an area the size of France and Germany combined have obliterated whole towns and left thousands homeless. Dozens more people are missing.

Floods have also ravaged Australia's other eastern states, with large swathes of New South Wales and Victoria inundated.

"Obviously it's not going to bring back some of the lives that have been lost but hopefully we can take some of the stress away," third seed Clijsters said on the arena's sun-drenched court.

With a mission of bringing some light-hearted cheer amid huge clean-up efforts, miked-up players clowned around the court, playing shots between their legs and mixing wisecracks with exaggerated grunts.

Caroline Wozniacki posed in a figure-hugging pink and white sports dress as Serbian world number three Novak Djokovic snapped her with a borrowed camera from the sidelines.

"I can see more than you think!" quipped Djokovic, waving the camera's extended zoom at her.

Ticket-buying spectators raised A$300,000 ($296,000) during the 'Rally for Relie'" event and corporate sponsors kicked in hundreds of thousands of dollars more.

Fundraising efforts will continue throughout the January 17-30 event, with players pledging to auction off their shirts and the governing bodies of the men's and women's tours donating A$10 for every ace hit in the tournament.

The Australian Open starts on Monday.