“Look, we’re the underdogs in this, without a shadow of doubt,” Ben Ainslie says calmly as he prepares for the greatest sporting challenge of his life against Team New Zealand in the America’s Cup, which begins on Saturday in Barcelona. “They’re the clear favourites but that’s a good thing. We’ve got pretty much everything to gain and nothing to lose. We’ve got the opportunity of a lifetime, so we’re really going to go for it.”

Ainslie won gold medals in sailing at four successive Olympic Games but even those achievements would be surpassed if he could inspire a first British victory in the 173-year history of one of the world’s oldest surviving sporting competitions. It is 60 years since a British boat was even in a position to race for the America’s Cup, which began on the waters around the Isle of Wight in 1851, and Ainslie and his Ineos Britannia team have just come through a bruising qualifying series.

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They have been racing competitively since August, as a round-robin series set up two knockout stages in which they outstripped their Swiss challengers before they were locked in a relentless struggle against an outstanding Italian boat, Luna Rossa, led by the grizzled Australian Jimmy Spithill. Day after day of gruelling skirmishes left them tied at 4-4 before, finally, Ainslie and his co-helmsman Dylan Fletcher found a way to crack open a decisive lead. Winning consecutive victories for the first time last Wednesday gave them the momentum they needed. Two days later their 7-4 series win meant that they clinched the Louis Vuitton Cup and the right to challenge Team New Zealand, the America’s Cup defending champions.

“It was a great moment for the team, really fantastic,” Ainslie says with a burst of exuberance before he hunkers down again in readiness for the New Zealanders who are led by Pete Burling. At 33 Burling is 14 years Ainslie’s junior but he carries an immaculate America’s Cup pedigree into a fascinating clash of style and character. In 2017 Burling became the youngest winning helmsman in America’s Cup history before, four years later, he skippered the Kiwis to a 7-3 cruise past Luna Rossa. That margin of victory seemed even more impressive as the Italian crew had crushed Ainslie and Ineos 7-1 to secure their place in the 2021 America’s Cup.

“My instinct tells me the boats are going to be a lot closer now than Luna Rossa were last time,” Ainslie says with a flash of the steel he will need against a New Zealand sailing team he has already lauded for emulating the mystique of the All Blacks. But Ainslie is as canny as he is tough and his praise for the Kiwis needs to be set against the words that Iain Murray, the regatta director, used to describe him last week.

Comparing the battle-hardened British crew to the lightly raced New Zealand boat, which has been lying in wait for the challengers, Murray said: “If you’re putting money on it the odds are that Ben will probably have an advantage at the start.” As an Australian who has been involved in eight America’s Cup events, half as a competitor, Murray offers vast experience and an acute insight into Ainslie whom he calls “unpredictable“, “ruthless” and “hard to handle”. Murray adds: “That’s all been part of his success over a very long period, so the Kiwis will have to manage that.”

Ainslie laughs drily when I read Murray’s description of him. “I’ve known Iain pretty much most of my competitive life and he was a very successful sailor in his own right. I’m not sure whether to take that as a compliment or not! But I’ve always pushed the boundaries and I think you have to do that if you’re going to be successful at the highest level. You’ve got to be prepared to take a few calculated risks.”

Murray delighted in the combative duel between Ainslie and Spithill as they raced hi-tech boats that can resemble Formula One cars on water. He said they were “back to fist-fighting of the first degree”.

Ainslie has never shied away from a scrap in a boat and, as Spithill was once a fine amateur boxer, had the standoff with the Italians felt like a bare-knuckle contest to him? “It was always going to be that way as Luna Rossa were an incredible opponent,” Ainslie says, “and Jimmy and I have got a great history of racing against one another. While it was incredibly intense, it was a hell of a lot of fun as well. I saw him in the mixed zone afterwards and I went over and we gave each other a hug. I’d just heard that he’d announced that he was going to hang up his gloves. I said: ‘Thanks for the moments. We’ve had a pretty good ride in our careers either with or against one another.’ It was quite an emotional moment, actually.”

Burling is of a different generation and Ainslie admits that “I’ve not raced against Pete so much. But Dylan beat Pete in the Tokyo Olympics [while winning the men’s 49er in 2021]. I know Pete pretty well. He’s an incredible once-in-a-generation talent with a really solid team around him. We know Grant Dalton is a serious player in the America’s Cup [having competed in six of them]. I worked with Team New Zealand in 2007 so I’ve got a good understanding of the way they operate and a lot of respect for that organisation.”

Last week Ainslie switched into pre‑race mind games when he suggested, a little wryly, that facing Team New Zealand “is like taking on the All Blacks in a rugby match when they’ve decided the size of the ball and the pitch”.

Ainslie seems remarkably relaxed now as he says, with another chuckle, “What I said was a bit simplistic but, ultimately, all credit to Team NZ. They are the All Blacks of sailing and their success in the last 30 years of America’s Cup sailing, since they started out, has been phenomenal. They’ve been the most successful team across that era. We also know that the defender in the America’s Cup calls the shots in terms of the venue, the timing and the class of boat. As challenger of record we get to negotiate some of those decisions but, when you’re up against such a strong New Zealand team as defender, it’s almost impossible to win.”

Pausing for a moment, Ainslie then makes a telling point: “I say ‘almost’ because that’s the key word.’”

“Almost” is also code for Ainslie saying, in his unpredictable way, that he believes his boat can win the America’s Cup. “Yeah,” he says with a laconic grin before serious battle begins, “I’ve always been a firm believer that, when you get an opportunity in life, don’t be afraid of it. Don’t be scared of taking on anyone. Just make the most of it and enjoy the challenge.”

There is less talk of being an underdog now. When he considers which team is in the stronger position – with the Brits being match-sharp but having been pushed to the brink of exhaustion while New Zealand could be either fresh or undercooked – Ainslie sounds full of realism and hope. “I don’t think there’s a lot in it, really, when you look at the different approaches we’ve taken to reach this point. We’re not in a position where we can stop, put the tools down for a week or so and recharge the batteries. So keep charging on. But the team are up for it and what an opportunity we have now. We’re ready to take it.”