New Zealand beat Britain in the opening America's Cup races on Saturday, 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.
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 New Zealand 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," Burling said 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," Burling added.
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.
"Not the start we were looking for," Ainslie said, while giving New Zealand credit for their performance.
"I'm confident the team can figure it out and come back tomorrow and look to get some scores on the board," he added.
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 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.
Italy won the first America's Cup for women on Saturday, beating Britain in the final. Italy also won the Youth America's Cup in the smaller AC40s used for the women's event.
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 Maori send-off before their boat was escorted away from their dock by a traditional waka canoe.