Sometime late Sunday afternoon on San Francisco Bay one of the world's best sailing crews will spray each other with champagne and be handed a cheque for $A1.4 million as the champion of SailGP's third season.

The odds favour it being Tom Slingsby and his deeply experienced Team Australia, who are going for a three-peat in tech tycoon Larry Ellison's global league aboard their foiling 50-foot catamaran nicknamed the Flying Roo.

They are the only crew to have clinched a spot in the three-boat Grand Final going into the San Francisco regatta.

The other two spots will be determined by three fleet races Saturday and two more Sunday.

Slingsby's rival from across the Tasman, Peter Burling of New Zealand, a two-time reigning America's Cup champion helmsman, is sitting comfortably in second. He must finish no worse than fifth in San Francisco to reach the winner-take-all Grand Final.

The final spot will be determined in a dogfight between upstart French skipper Quentin Delapierre and Britain's Sir Ben Ainslie, who sit just one point apart in third and fourth.

Slingsby, an Olympic gold medallist and former America's Cup champion, has dominated SailGP since it was founded by Ellison and New Zealander Russell Coutts, a five-time America's Cup champion.

"It's a confidence thing," Slingsby said on Friday. "It's a simple sport if you do the simple things right - get a good start, don't make mistakes, sail the boat fast, do what we know we can.

"But at a venue like San Francisco, it's windy, we're up against the best teams in the world and they're going to be trying to rattle you, put you off your game, get you off your foils, all those little things that can really just take us down."

But Slingsby added the confidence was high.

"I feel like we're in a good position. We're the only team who has been to the final race before. As much nerves as we have, I think the other teams might have a bit more nerves heading into that final and that's a nice place to be."

Slingsby is familiar with sailing on San Francisco Bay. He won SailGP Season 2 championship there last year and helped the Ellison-owned Oracle Team USA win the 2013 America's Cup in an epic comeback against Emirates Team New Zealand.

The Aussies won three of the 10 previous SailGP regattas this season and reached the three-boat podium race in five others. The Kiwis also have won three times - twice beating the Aussies - and reached two other podium races.

France have won twice while Ainslie - the most decorated sailor in Olympic history with four gold medals and one silver - has failed to win any of the four podium races he's reached.