TONIGHT, Roger Federer and Lleyton Hewitt will help launch a “game changing” new tennis format in Sydney.

This is how FAST4 works.

THE RULES

* Singles matches will be played as the best of three short sets.

* Each set is the first to four games, with a short tiebreak to be played at 3-all.

* The tiebreak is first to five points, with a sudden death point at 4-all.

* There is no advantage scoring in games. At deuce, the receiver will choose which side of the court the ball will be served to for a sudden-death point.

* No service lets will be called, meaning that when the ball hits the net cord on a serve and bounces in the right service box, it’s play on.

* At the change of ends, players are not allowed to sit down. Play must continue within 60 seconds.

* There will only be a short break of 90 seconds between sets. Players are allowed to sit down at this point.

Click here for more detailed FAST4 tennis rules

WHAT’S THE POINT?

Developed in Australia, it is being billed as tennis’ version of Twenty20 cricket.

“The new format is a game changer and is set to revolutionise the game of tennis, particularly at club and social levels,” Tennis Australia CEO Craig Tiley said.

“Time today is precious and this new fast format is perfect for any player who wants to fit their tennis matches into a busy lifestyle.”

WHERE IS IT?

Tonight’s matches will be played at Sydney’s Qantas Credit Union Arena, formerly known as the Sydney Entertainment Centre.

On Wednesday night, Melbourne’s Margaret Court Arena will play host.

WHO’S PLAYING?

Roger Federer vs Lleyton Hewitt is the marquee match-up tonight.

On Wednesday, Rafael Nadal will face three opponents in separate matches: one set against former US Open finalist Mark Philippoussis and another against reigning US Open junior champion Omar Jasika, before a best-of-five-sets match against Spanish countryman Fernando Verdasco.

WHERE CAN I WATCH IT?

Channel 9 will broadcast the exhibition tournament from 7.30pm around the country tonight and Wednesday night (live in Sydney and Melbourne, delayed in Brisbane, Adelaide and Perth). Hobart viewers can see it on WIN from 7.30pm local time.