Ineos Team UK have remained unbeaten in the Prada Cup, beating American Magic in their only race on day two.

But for the Americans, led by Kiwi Dean Barker, it was a second horror day on the water as they suffered a third defeat and tumbled from pre-regatta favourites to now being regarded as the weakest challenger on display.

The frustration seemingly got to Barker who, after the first race of the day - defeat to Jimmy Spithill's Luna Rossa in very light breeze - expressed his displeasure with the decision to go ahead with sailing despite the low winds.

"[You could] call that a lottery yeah … pretty marginal. You question why you want to do that as part of the event. But it is what it is. Swings and roundabouts and it obviously didn't go that well for us," Barker said in what was seemingly a veiled dig at officials.

When asked why American Magic didn't go with bigger headsails, Barker said: "Leading up to the start we didn't expect to be sailing in that light a breeze. It was a bit of a surprise that it got so light.

"It is just connecting the dots. Everyone is struggling."

In what had previously been an area of concern for Ineos Team UK, the British entry showed plenty of improvement in the light winds to claim their third straight win.

As they did on opening day, Sir Ben Ainslie's crew got the better of the start which put them in position to control the course.

The British team managed the patchy conditions better, and led by more than 1600m after the third leg.

In the end, it became a race against the clock for Ineos Team UK, who had just under seven minutes to finish the final leg and beat the 45-minute time limit on the race.

They did so with about two minutes remaining, at which team skipper Sir Ben Ainslie said "good sailing".

The Americans also suffered a nightmare start to the first race - after unsuccessfully appealing for a penalty on the Italian following a close cross in the pre-start, both teams dropped off their foils and were already having to work hard to get flying again.

The Italians did so before long, while the Americans remained beached for much of the remaining two minutes before the start.

As Luna Rossa flew down the first leg, American Magic again fell off the foils midway through the leg, and were racing in displacement until just before the marker, which they rounded more than seven minutes after Luna Rossa.

But while American Magic had their struggles in the opening leg, Luna Rossa had their own in the second. The Americans quickly ate through the lead as Luna Rossa couldn't get foiling and halfway down the leg found themselves in the lead.

Both teams' struggles to stay up saw the race shorted from six legs to four early in the second leg.

Soon after, Luna Rossa flew back into the lead as they were able to get up on their foils before their counterparts to lead by one minute at the second marker.

From there, they never relinquished the lead – managing to chase the breeze all the way down the last leg to stay on their foils the whole way down and close out a strange race.