Fan numbers watching on Sunday eclipse audience for previous night's rugby test.

More than half a million Kiwis tuned in to watch Team New Zealand beat Oracle in the first races of the America's Cup on Sunday.

The audience topped the number who watched the All Blacks play Argentina the night before by more than 12,000.

The average audience for the first two races was 522,720, which peaked at 669,200 viewers at the end of the second race.

The test match against the Pumas reached an average audience of 508,500 viewers with the peak reaching 535,100.


Fewer tuned in for races three and four on Monday morning, which had an average audience of 280,500.

The audience for this year's sailing event has already beaten the highest rated race in the 2007 America's Cup in Valencia which 270,300 people watched. However, those races were held between 1am and 2am NZ time.

TVNZ's head of television, Jeff Latch, said the network was "rapt with the performance of the America's Cup live match races".

The Sunday morning races won 63 per cent of the audience at the time - more than three times higher than the closest comparable race in 2007.

"We expect numbers to build, particularly if Oracle win one or two more races as it gets closer to the end," Mr Latch said.

Herald head of news and online editor Cathy O'Sullivan said there had been huge interest in the Cup among readers in the past week. Stories, video and comment pieces on the event had been among the most read and watched pieces of content across all of the Herald's online platforms for the past week, she said. "The live updates on race three and four on Monday saw huge engagement."

Follow all the action from races five and six from 8am.