America’s Cup officials have said they made a mistake in awarding the penalty that cost Artemis Racing victory in their match against Emirates Team New Zealand this afternoon.

On a day of upsets, drama and controversy, the Swedes were penalised at the final mark of a see-saw battle with Team New Zealand after being adjudged not to have given their opponents enough room to manoeuvre.

Artemis were flying for home by the time they realised they were under a penalty, and Nathan Outteridge, the helmsman, was still not happy with the on-water ruling more than an hour after the fact.

It turns out he had good cause.

In a statement, the America’s Cup Race Management group said that in hindsight the decision to penalise Artemis was not the right one.

“As in all sports, umpires are not infallible and on this occasion, even with the best sailing umpires in the world that are overseeing the 35th America’s Cup they have admitted that their decision, on reflection, may have been different,” the statement read.

Richard Slater, ACRE’s chief umpire, added: “When they [the teams] were coming down to the final gate mark, with the information we had at the time, we had Artemis Racing on port, as the keep clear boat, and Emirates Team New Zealand on starboard, and our job is to be certain that Artemis Racing were keeping clear, and we weren’t at that time certain they were keeping clear.

“We have had a discussion, we have looked at other evidence, information and data, and I think if we were to go back in time and make that call, we would green that call [give them the green light] and not penalise Artemis.”

Not that any of this is of consolation to Artemis. The result cannot be overturned.

The admission capped a thrilling day of racing, in which Artemis and New Zealand produced the best race of the Louis Vuitton America’s Cup Qualifiers. And it was a tale of two penalties.

After boxing in New Zealand at the start, Artemis crossed the line a fraction of a second too soon and, having raced to the first mark, dropped back to allow New Zealand to go ahead.

It was the first of ten lead changes throughout a race that was nip-and-tuck right until the two teams, who reached 40 knots at times, headed to the final gate. With Artemis on the outside, and Emirates taking the inside tack, the Swedish team were penalised for not giving their opponents enough room around the turn.

“When you’re coming out at 40 knots, you need a little bit more room than that” was the assessment of Peter Burling, the New Zealand helmsman.

The Swedes, unaware of the penalty flag, raced to the finish line for a win that would have helped to erase the disappointment of the loss to France yesterday. Instead, they slowly lost speed as the realisation of the situation grew on them.

In a slightly surreal ending, the New Zealanders chased Artemis down the finish shoot, with Artemis finishing the race as they began — a fraction in front, but with a penalty negating their position.

Understandably, Burling was in no doubt as to the righteousness of his side’s cause. His counterpart on the Artemis boat, Outteridge, was less impressed. Christian Kamp, a reserve grinder for the Swedish team, summed up his side’s feelings as diplomatically as possible.

“I’m not happy with that penalty, I didn’t see anything wrong with it [the manoeuvre],” he said.

If the second race provided the drama, the upset came at the start of the third day of the America’s Cup as Groupama Team France, long considered favourites not to progress beyond the qualifiers, proved that their win over Artemis Racing was no fluke, picking up another victory, this time over Land Rover BAR.

Franck Cammas and his team fought back from a slow start and made the most of two mistakes from Sir Ben Ainslie, the most serious of which when going upwind at gate five handed the French a lead they did not lose.

In the end, BAR finished some 53 seconds adrift and have now lost four of their five races. If not for the bonus points accrued during the World Series, BAR would be adrift at the bottom of the table.

Cammas did not have it all his own way today; Dean Barker made sure of that. The New Zealander, who has made fast starts his hallmark, got his SoftBank Team Japan side off to another one and never looked back.

Going ten knots faster than the French at the start, SoftBank eventually won by a healthy 2min 34sec.

Meanwhile, SoftBank’s win in the final race has made things tight at the bottom of the table with themselves, Artemis and France all on two points. There is not much to chose between those at the top, and the day’s big winners may well have been Oracle Team USA; even though they did not race.

They now have a two-point cushion over Ainslie and BAR, and are a point ahead of Team New Zealand.