Sir Ben Ainslie will be looking skywards and praying to the wind gods after seeing his unbeaten record ended at the America's Cup.

The Team Ineos UK skipper slipped to two defeats to Italian rivals Luna Rossa in the opening exchanges of the best-of-13 Prada Cup final in Auckland, the winner of which will go on to face Team New Zealand for sport's oldest international trophy next month.

Ainslie had won their three previous clashes but found himself becalmed in windless conditions, Britannia's well documented issues in light air obvious as Luna Rossa sailed clear to win their first race by nearly two minutes.

The second race was closer in a much steadier breeze but Luna Rossa's superior boat speed and flawless tactics secured a 26 second win.

"We came up short but tomorrow we won't," said Ainslie. "It was a frustrating day but there is a long way to go in this series. 

"The Italians sailed really well but we'll keep pushing, there's seven more races to win and we just need to be faster.

"We've got to sail better, especially in the lighter airs, and we've got a jump to make to catch up with these guys. We've improved a lot in lighter airs but obviously not enough.

"We're two very even teams at over ten knots of wind but those conditions they've got the edge, we need to find that extra speed.

"It's great to be up against tough competition but we're not happy to be two-nil down. We're going to push harder and harder to get those races back.

"The forecast tomorrow is for more breeze so hopefully we'll be able to get stuck in."

Luna Rossa's helmsman Jimmy Spithill was smarting after their previous encounter a fortnight ago, a close quarters high seas battle that saw the lead exchange hands nine times before Ainslie emerged victorious.

A two-time winning America's Cup skipper known as Pitbull, he was off the leash for this, shouting 'never in doubt' as his boat crossed the finish line.

"It's only two wins in a long series and we're going to see a lot of close racing, we're taking nothing for granted," said Luna Rossa's skipper Max Sirena.