Sir Ben Ainslie and his Land Rover BAR team booked their place in the Louis Vuitton America’s Cup Challenger Play-offs yesterday, but the size of the task they will face there was brutally underlined when the Briton voluntarily retired from a race for the first time in his career, as they were crushed by Emirates Team New Zealand on another day of light winds on the Great Sound.

While Ainslie’s team have shown that they can perform well in winds of about 12 knots, when the breeze drops towards the permitted minimum of six knots, they are struggling.

New Zealand’s dominance over BAR was so complete that Ainslie retired with 1½ legs of the race remaining, aware that they had another race to compete in yesterday. They won that race, in excruciatingly tight fashion over Groupama Team France, but it looks increasingly likely that the French will be the one team not the make it to the play-offs, which start on Sunday.

“It was a tough day, we were really struggling on out light-air set-up,” Ainslie said. “The guys really had to dig deep and get around the course.

“The super-light air is a real Achilles’ heel for us right now. From our reconnaissance, we could see it was an area where we would struggle.”

There were plenty of rumours that New Zealand would be strong in light winds, as their cycles give them the power edge over the conventional hand grinders on the other boats, but the margin of dominance was impressive on an afternoon when most other teams spent a fair amount of time bobbing about in the water.

Ainslie continued his fantastic record by winning both starts on the day — the only start he has not won this week was when he collided with France — but New Zealand were picking up more speed at the first mark when BAR came crashing down off their foils on their very first gybe.

“What happened?” Ainslie shouted as New Zealand vanished into the distance, and a slight lead turned into deficit of more than three minutes at the second mark, which they barely floated past.

Ainslie later said that the boat had suffered a system failure. “We couldn’t control the starboard daggerboard, so it was in its maximum position and drove us forward on to our bows and stopped us dead,” he said. “Whenever we were gybing, we were having a similar problem. We decided we were miles behind and had a big race against France coming up, so let’s pull out and give the technicians enough time to fix it.”

BAR’s race against France was a tight affair, with both crews struggling to build enough speed to get on their foils. It was so slow the race was reduced from seven legs of the course to five.

While BAR began well when Ainslie forced a penalty from France in the starting box, France passed them on the second leg. The race stayed agonisingly close, as neither could find a strong-enough breeze and was not settled until the final moment, when Ainslie managed to get the advantage of the starboard side into the finish and close out the win.

“I can’t say it was the most fun race I’ve ever been involved in when we were struggling downwind like that,” he said. “But the guys kept going and kept digging, and it was a great win in the end. It was certainly a race we won’t forget for a while.”

The breeze was light enough that racing was delayed on two occasions throughout the afternoon after it has been abandoned altogether on Wednesday. Stronger breezes are expected from the weekend on.

Land Rover BAR do not race today, but will be out on the water testing as they look to find any improvements they can.

“We can have more of a development focus over the next couple of days, then a racing focus now we have secured our place in the play-offs,” Ainslie said. “We probably will try and rest a couple of the guys and keep the rotation going.”

A place in the play-offs was already assured the moment that Japan had beaten France in the day’s first race by an enormous 5min 59sec.

New Zealand’s victory was matched by Oracle Team USA, who beat Japan on the day, as the two teams that contested the last America’s Cup continue to look dominant.

With New Zealand expected to be the highest-placed challenger in the Qualifiers, they would get to choose their opponents in the best-of-nine semi-finals.