BARCELONA (Reuters) -New Zealand stretched their lead to 4-0 in their America's Cup defence on Monday, leaving challengers Britain to work on ways to win the next showdown after losing out to the holders in a tacking duel and a series of downwind crosses.
The New Zealanders ultimately managed to get slightly more performance out of their AC75 monohull "Taihoro", piling the pressure on British skipper Ben Ainslie during the closest race so far in the first-to-seven-wins series against "Britannia".
Ainslie's team, still smarting from an umpire's decision that went against them in one of the pre-starts on Sunday, again protested against the New Zealand team during a series of close crosses as the boats sped downwind.
"We are going to keep going and push all the way here, we can still come back from this," Ainslie said on the America's Cup live broadcast after Monday's single scheduled race.
The British sailor was part of a U.S.-led team that made one of the biggest ever sporting comebacks against New Zealand to win the America's Cup in San Francisco in 2013.
Ainslie said that a reserve day on Tuesday would give the crew a good opportunity to work on ways to narrow the slight performance gap they were seeing against New Zealand.
Dylan Fletcher, Ainslie's co-helm, said the team still disagreed with Sunday's decision of the umpires and felt a lot of calls had gone against them in their pursuit of the America's Cup, which Britain has not won in its 173-year history.
"The Kiwis chose to engage with us," Fletcher said of Sunday's near-miss, adding that the decision was frustrating and he felt the British had done everything they could.
"I think where we have left it is that we've agreed to disagree," America's Cup chief umpire Richard Slater said of an intense meeting with the British and New Zealand teams.
UMPIRE-SAILOR FRICTION
Slater said during a pre-race briefing there was always tension between umpires and sailors during any competition and the officials did not want the boats to be close, adding that "these boats are doing things that normal boats do not do".
But both teams understood that any contact between the boats was not a good thing, said Slater after regatta director Iain Murray earlier warned that if they had collided it could have led to a sinking given the huge forces involved.
New Zealand's ever-relaxed skipper Peter Burling said the disputed incident, during which race officials said the speeding boats came within metres of clashing, would not change the way he approached the critical pre-start manoeuvres.
"I thought it was pretty clear cut and I'm a bit confused why the British are complaining to be honest," Burling said.
"If they are going to leave themselves open, we're going to take the opportunities. They've been doing that for quite a while and it's obviously something we've studied and want to take advantage of," the 33-year-old added.
"Really happy with a lot of our race craft today, feel like we did a really good job around the course. Saying that, it's obviously a little bit harder when you're on the back foot off the start," Burling told reporters after Monday's win.
Fletcher said the British still had improvements to make as they analysed data from both boats, with their partners at the Mercedes Formula One team providing valuable input.
Races five and six of the America's Cup final series are scheduled to take place on Wednesday.
(Reporting by Alexander Smith; Editing by Ken Ferris and Andrew Cawthorne)