Holders Team New Zealand roared back to beat Luna Rossa and make it 3-3 in the 36th America's Cup match off the coast of Auckland on Saturday, after the challengers dominated the day's opening race.

The Kiwi boat hit speeds of over 40 knots in the second race to cross the line one minute and 41 seconds ahead, to the delight of most of the roughly 15,000 fans on the quay and some 2,000 spectator boats by the course.

"That was a good one, to have the boat speed like that," Team New Zealand flight controller Blair Tuke said.

"The big speed difference was very pleasing and just like yesterday, a really good reply from the guys. A good way to finish another tight day.

It was the perfect response from TNZ, who lost the first race by 18 seconds after a poor start in which they were forced to delay and could not get up on their foils. The Italians led throughout following a starboard entry - the first time in the match a team had managed the feat after the previous four races were won by the vessel that started from the port side.

But Luna Rossa, who excel in light winds, failed to build on their advantage and Australian co-helmsman Jimmy Spithill was left to rue a slow start that cost them the second race.

"We were happy with our positioning; unfortunately we got caught in a light spot and couldn't get the boat going back to the line, almost a reversal of the first race," Spithill said.

"Not a lot of passing lines from then on ... It's just one of those things. It's a bit of a minefield out there from the start box and we couldn't get the boat to accelerate. The goal is to win one (race) at a time, we're not looking too far ahead."

"There will be a lot of lessons learnt from both races and we'll come back stronger and ready to roll ... This is what we live for, what it's all about."

The teams will face off in two races again on Sunday in the best-of-13 series for the oldest trophy in international sport - the 170-year-old "Auld Mug" - with stronger wind strengths predicted.