HAMILTON (Bermuda) • Defending champions Oracle Team USA clawed their way back into sailing's America's Cup on Saturday with a much-needed win over Emirates Team New Zealand to reduce their deficit to 4-1 in the first-to-seven final.

The US victory in the second race of the day gave the team backed by billionaire Oracle founder Larry Ellison hope of another comeback against New Zealand.

Oracle Team USA won the Cup in 2013 in San Francisco after staging one of the most astonishing sporting comebacks against New Zealand, winning 9-8 after going 8-1 down.

The US team have spent the week working on making improvements to their 50-foot foiling catamaran in an effort to match the superior speed of their rivals, who are using a revolutionary cycling system with which their sailors provide the power needed to control the boat.

"That was exactly what the boys needed... we've had a good improvement on our boat speed today and I think another step tomorrow would be great," US skipper Jimmy Spithill said.

"We worked very, very hard those five days and we sailed probably five times as much as the other guys and did a lot of work on the shore and I'd just like to see the boat go quicker."

The rivals are due to resume battle on Bermuda's Great Sound this morning (Singapore time), with another two races scheduled.

The US win means the racing could continue beyond today.

"It was great to see those boys actually sailing a little bit better… these guys just sailed well and we're just excited about the battle ahead," New Zealand helmsman Peter Burling said after the rare defeat.

Things started badly on Saturday for the US team as they were a fraction of a second over the line at the start of the first race, picking up a penalty which left them trailing.

Although the New Zealand team got away, the champions recovered well and fought their way back into the race, finding the speed which had evaded them in previous encounters.

REUTERS