Clinical Team New Zealand dominate Britain in opening America's Cup races

New Zealand beat Britain in the opening America's Cup races, with the holders setting the pace in the early skirmishes with the challengers in the first-to-seven contest.

The wins give New Zealand a 2-0 lead, with co-helms Peter Burling and Nathan Outteridge delivering two calm and clinical performances in light Mediterranean winds off Barcelona.

"We've done a lot of work making sure we are ready to go," Burling, 33, said on the America's Cup live broadcast from aboard his AC75 boat after finishing the second race.

"Nice way to start," added Burling, before the New Zealand boat was towed back into port, flanked by spectator vessels.

Britain had a last-minute scare just before the start of their first race when one of the batteries which power the boat's foils had "a bit of a meltdown" and had to be removed "in a bit of a hurry", their skipper Ben Ainslie said.

The incident meant the British were slightly on the back foot coming into the first pre-start, with the New Zealanders steaming over the line and getting a jump on the first leg.

"Awesome to get a couple of wins on the board. A really tricky day. So shifty, dynamic, up-down. But really pleased with the way the group managed to make more good decisions than not," said Burling, 33, after the races.

"We're really happy with the way that we went out and performed and we know that we are going to have however many tough races from here," he added.

British skipper Ainslie and his team qualified as challengers in the duel for the "Auld Mug", which was first raced in 1851 and is billed as the oldest trophy in international sport, for the first time in 60 years.

"A tough day. It wasn't the start we were looking for but some positives ... Whilst they had a little edge at times it was close and certainly that second race showed we can give them a good fight," Ainslie said back ashore.

"There's plenty we'll take away in terms of improvements to make and it's a long series ahead," he told reporters.

Data from Saturday's races will be closely analysed by both teams as they seek to find ways to eke more speed out of their boats and crews.

An old adage among America's Cup followers is that "the fastest boat wins", with the two high-tech AC75 foiling monohulls set to be put to the test in the week ahead.

"The difference in boat speed definitely gets exaggerated when you can get on some (wind) shifts as the leader," Burling said when asked about the relative performance of the boats.

The 37th cup is being contested off the Spanish city of Barcelona, where variable winds and unstable sea states in the qualifying events have made sailing conditions challenging.

Also on Saturday, Italy won the first America's Cup for women, beating Britain in the final. Italy also won the Youth America's Cup in the smaller AC40s used for the women's event.

'Bring the cup home'

Ainslie's decade-long campaign to "bring the cup home" has been backed by British billionaire Jim Ratcliffe, who was on the water to see the historic encounter, and they have worked closely with the Mercedes Formula One team to come up with a race-winning package and end "173 years of hurt".

Britain battled their way to challenge New Zealand by beating Italy 7-4 in the Louis Vuitton Cup, with Ainslie's team showing improved speed and handling through the qualifying races as they tweaked both their boat and sailing technique.

New Zealand had been practising alone and making changes in the lead up to the clash, with team boss Grant Dalton saying he expected the AC75s to be "pretty equal" in speed, meaning getting off the start fastest gave a greater chance of winning.

Earlier, there was a party vibe at the British base with tunes from DJ Rob da Bank as the crew docked out, with horns blaring and fans waving flags as the sailors and their support crew pulled away from their base.

Hundreds of New Zealand supporters sporting black kit, with many draped in the country's flag, had cheered the Kiwis as they were given a Māori send-off before their boat was escorted away from their dock by a traditional waka canoe.

- Reuters