Tom Slingsby of Team Australia has claimed a third-straight SailGP season championship, surviving a few tense moments to cross the line first in the $US1 million, winner-takes-all deciding race.

The experienced skipper kept his cool when his catamaran fell off its foils in the grand final before outsprinting Peter Burling of New Zealand in a short dash to the finish on San Francisco Bay.

Slingsby, who has dominated tech tycoon Larry Ellison's global league since it debuted in 2019, dodged what could have been a huge embarrassment when he recovered and kept his 50-foot Flying Roo ahead of Burling for the thrilling victory.

British sailing star Sir Ben Ainslie finished a distant third.

"That was not the plan. I thought we lost it," a relieved Slingsby said right after the race.

"We had it the whole way. That was crazy. I was very scared.

"I was thinking, 'This could be the biggest choke of all time right now'. But fortunately we were able to get it over the line. What a race."

Slingsby and his four-man, one-woman crew celebrated by spraying each other with champagne and unfurling an Australian flag.

A few minutes earlier, it looked as though they might have been left devastated.

Slingsby led at every mark after pushing the British back during the pre-start and then forcing the Kiwis wide at the first mark.

The Aussies had a lead of about 100 metres approaching the fifth mark but came off their foils after a tack and slowed considerably, allowing the Kiwis to close to within 30 metres.

Slingsby crossed just ahead of Burling and then tacked, staying barely ahead around the mark and then speeding across the short reach to the finish.

"We had such a comfortable lead and then I decided that I wanted to sort of shut the race down a bit and do extra manoeuvres to make sure they don't get different wind," Slingsby said.

"In the end, they didn't really get different wind but they were tacking in better positions and they were able to foil out of the tacks a bit better than we were.

"We were tacking in less wind and they just kept gaining, kept gaining and fortunately we ... were able to hold on to the finish.

"The fact that we got the job done today is a huge testament to these people," he said of his crew full of Olympic and America's Cup veterans.

"I'm so thankful to have such an amazing team.

"Our run is going to come to an end eventually, but we just want to extend it for as long as we can."