The hottest rivalry in sailing heads across the pond to Old Blighty, where Sir Ben Ainslie and his British crew will face the tall task of defending home waters against Tom Slingsby and his crew of seemingly unbeatable Australians.

Team Australia will try to run its SailGP winning streak to six during the Great Britain Sail Grand Prix Plymouth on Saturday and Sunday. The Aussies won the Plymouth regatta last year while Britain finished fourth, with Paul Goodison filling in for Ainslie while the national star was with his wife for the birth of their second child.

The Aussies have largely dominated tech tycoon Larry Ellison’s global league since its inception, including winning the championship and a $1 million check each of the first two seasons. They’ve won seven of the last eight regattas spanning two seasons.

Ainslie, the most-decorated sailor in Olympic history, has also sailed spectacularly at times since joining SailGP, and his rivalry with Slingsby has been elevated to the point that it’s being called ”Ashes on Water,” a comparison to the long-running cricket rivalry between the countries.

Slingsby hasn’t been shy about talking about the brimming confidence of his crew, which is loaded with America’s Cup and Olympic veterans. Days before the Chicago SailGP regatta last month, Ainslie mentioned the Aussie team’s confidence as being a big motivator ”to try and beat that and take that down. I think it’s a dangerous line to tread.”

Slingsby and crew then did what they’ve done best recently. They came on strong on the second day of fleet racing to sneak into the three-boat podium race and then sped off aboard their foiling 50-foot catamaran to victory against Canada and Great Britain.

Slingsby is still as confident as ever, especially after winning in the historic southwest English port last year.

”I’m sure Ben and his team have done plenty of sailing around Plymouth before, definitely more than us,” Slingsby said. ”So, you’ve got to think there is some home-field advantage there, but we did well here at this event last year so we feel pretty confident as well in these conditions.”

Slingsby and Ainslie, who each won a gold medal at the London Olympics 10 years ago, were crewmates aboard Oracle Team USA in the 2013 America’s Cup. They helped helmsman Jimmy Spithill – now the skipper of SailGP’s Team USA – stage a stunning comeback to beat Emirates Team New Zealand and retain the Auld Mug.

Now they’ve got a pretty good rivalry going.

”I guess it’s turning out that way,” Slingsby said. ”Ben and I used to be pretty good friends but we probably talk a little bit less than we ever have. I guess competition just does that to you. I think it’s a pretty healthy rivalry. They’re one of the best teams and so are we.”

Ainslie said it’s a bit early in the season ”to start picking rivalries, but for sure the Aussie team is doing a fantastic job of setting the standard, really. So, I think for myself and the rest of our team, that should be great motivation whenever you’ve got somebody like that or a team like that out there and they’re obviously feeling good about how they’re going.”

Ainslie said he and Slingsby are still mates off the water, ”and we always will be.”

Ainslie said that while members of his crew have sailed in Plymouth before, he hasn’t sailed there since he was 15.

”The other thing, of course, is having the home crowd giving you that little bit of extra motivation,” Ainslie said. ”You want to try to put on a good show for them, which definitely will make a difference.”

Ainslie said he’ll also be motivated by the 10th anniversary of the London Olympics. Ainslie capped his Olympic career by winning his fourth straight gold medal and fifth overall up the coast at Weymouth.

Australia leads Canada and Britain by three points in the overall standings. They’re followed by New Zealand, Denmark, France, the United States, Spain and Switzerland.

Follow Bernie Wilson on Twitter at http://twitter.com/berniewilson