Underdogs Groupama Team France won their first race of the America's Cup in Bermuda on Sunday, while defenders Oracle Team USA tasted defeat for the first time in the contest.
Artemis Racing, the pre-event hot shots, were beaten by the French team in a thrilling duel, with the two high-tech 50-foot (15 metre) catamarans reaching speeds of up to 40 knots as they screeched across the crystal-clear waters of the Great Sound.
The Swedish team made amends in their second race by ending the three-race winning run of Oracle Team USA with a convincing show of tactics and boat speed giving them victory by a 39-second margin after they took the lead from the start.
It was not all bad news for the U.S. crew, however, with a win in the head-to-head between former team mates Jimmy Spithill and Land Rover BAR skipper Ben Ainslie. The pair showed initial wariness, with Ainslie, the most successful Olympic sailor ever, getting the advantage at the start and the early lead.
There were doubts over whether Ainslie would be able to race at all after he holed his catamaran "Rita" in a clash with SoftBank Team Japan during the opening day of the qualifying races.
While Land Rover BAR showed good speed on Sunday, the U.S. crew's tactician Tom Slingsby made a shrewd call on the third leg of the seven-leg course and Oracle Team USA were able to pass their British opponents for a clear win.
"It was just smooth sailing and no panic," Spithill said after the race, adding that he was "not yet satisfied" with the performance his crew were getting out of their catamaran.
"The boat is getting quicker every day and we just need to keep that going," Spithill added.
In their final race of the day, Spithill's crew scored a convincing win over SoftBank Team Japan, who had earlier lost to Emirates Team New Zealand.
The match between the Japanese crew and the New Zealand team was a poignant one for SoftBank Team Japan skipper Dean Barker, who was dropped by Emirates Team New Zealand after he lost the 2013 America's Cup to Oracle Team USA in San Francisco.
New Zealand also dominated Ainslie's Land Rover BAR, despite incurring a penalty during the starting manoeuvres. Skipper Glen Ashby's crew overhauled the British team for a resounding win.
Although the wind was shifty and died slightly towards the end, conditions in Bermuda's Great Sound were once again ideal, with the flat water allowing the boats with their towering "wing" sails to "fly" on their foils.
Groupama Team France had appeared to struggle to keep their boat on its foils during some manoeuvres on Saturday, with their hulls occasionally ploughing into the water.
But on Sunday, it was Ainslie's Land Rover BAR who seemed to struggle at times with controlling their boat. In both their races the British crew gave ground when they lost their grip on the water and nose-dived one of their hulls.
(Reporting by Alexander Smith in London; Editing by Clare Fallon and Pritha Sarkar)