Team New Zealand and Luna Rossa of Italy head out to contest the America's Cup on Auckland's Waitemata Harbour Wednesday in a nautical showdown where the result relies on technological gains as much as sailing prowess.
Racing for the world's oldest sporting trophy now takes place between cutting-edge "flying" yachts inconceivable when the event was first staged 170 years ago.
The boats feature carbon-fibre foil arms, which lift the 23-metre (75-foot) hull above the surface of the water, achieving speeds exceeding 50 knots while balanced precariously in mid-air.
Defending champion Team New Zealand, after success with traditional displacement yachts, pioneered foiling in the America's Cup with a prototype catamaran developed in 2012.
When images of the boat emerged online, the concept seemed so bizarre that critics insisted they were photo-shopped.
The New Zealanders have remained at the forefront of research and development, making them short-priced favourites in the best-of-13 America's Cup final.
They have reached the final in six of the past seven regattas for the fabled 'Auld Mug', winning three times in 1995, 2000 and 2017.
Team New Zealand also dominated warm-up racing for the latest edition of the cup late last year, showing superior boat speed and competitiveness in all wind conditions.
Luna Rossa's co-helmsman Jimmy Spithill described his rivals as the best team in the world.
"To be able to race Team New Zealand on (their) home waters, it's a lot like a rugby player getting to go on the rugby field against the All Blacks at Eden Park in a Rugby World Cup final," he said.
"What an incredible privilege that is."
- 'Sudden death, real pressure' -
Spithill's Luna Rossa slipped under the radar in preliminary racing, overshadowed by high-profile rivals Ineos Team UK -- featuring British sailing legend Ben Ainslie -- and American Magic, backed by the prestigious New York Yacht Club.
But the Italian syndicate steadily improved throughout the challenger series, seeing off American Magic 4-0 in the Prada Cup semi-finals, then Ineos Team UK 7-1 in the final.
Spithill said his team was match-fit, while Team NZ had not raced competitively since late December, despite logging hundreds of hours' practice.
"We've had real racing, that's the difference... we've had sudden-death, real pressure -- they've had to train on their own," the Australian said.
In general, Luna Rossa is seen as strong in lighter winds, while Team NZ has the better overall package.
But the AC75 yachts are a "development class" created specifically for this event, meaning design tweaks and innovations are constantly occurring, even as racing takes place.
As a result, there's scope for significant improvement between races as design changes are implemented and crews become more adept at handling the space-age vessels.
Former round-the-world yachtsman Knut Frostad, whose company Navico produced the navigation systems used by several America's Cup teams, said Team NZ appeared to have an edge.
"But it is far from certain," he told AFP.
"With the AC75s, the potential gains if you have a technological breakthrough are so big that any of the team could still be making big improvements even after the first match in the America's Cup," he said.
The start of the regatta was delayed by several days after a Covid-19 outbreak forced host city Auckland into a snap lockdown.
While stay-at-home orders have been lifted, there are still limits on social gatherings, meaning large crowds cannot watch the races from Auckland's shoreline as organisers originally intended.
Regardless of technology or crowd numbers, the America's Cup will be contested with the same vigour displayed during the inaugural race off England's Isle of Wight in 1851, which took place in front of Queen Victoria.
Watching from her royal yacht, the monarch turned to the signal-master as the successful American challenger hove into view and asked which of the local boats was in second place.
"Ah, your majesty," came the reply. "There is no second."