A challenge for the 37th America's Cup has already been issued and accepted, with the start of the process beginning out on the water as soon as Team New Zealand secured the Auld Mug earlier on Wednesday.

Royal New Zealand Yacht Squadron general manager Hayden Porter confirmed the club had received a new challenge when speaking to Newstalk ZB's Heather du Plessis-Allan this afternoon, but would not say where the challenge had come from.

"We have received a challenge for the 37th America's Cup. There's a lot of details to come; discussions will evolve over the next few days, weeks and months and things will happen from there ... it was all done out on the water – all details will be revealed in the next wee while," Porter said.

There have been suggestions the challenge has come from the Royal Yacht Squadron from the United Kingdom, with RYS commodore James Sheldon in Auckland with his associates.

As first reported by the Herald yesterday, the RYS is the preferred Challenger for the next regatta - which means that Ben Ainslie's Ineos Team UK would be in line to represent COR in the next Cup.

Porter said there was exchange between "the two commodores" which suggests it was Sheldon and RNZYS commodore Aaron Young.

The process of agreeing terms with the next Challenger of Record is remarkably swift - as the deed of gift allows for any other yacht club to put in a challenge, that must be accepted should it be considered "legitimate" - and it will be no different in this case.

"It's one of those traditions that is pretty special about the Cup; that they must receive a challenge and it must be accepted," Porter said.

"There's a protocol that goes with it; it gets handed over literally at the second it happens. In the old days, things used to get thrown on to boats. Here at the club, we have some protocols that go around it where our email servers get shut down, our phones get shut down, the doors get locked and things like that so it can't be challenged that another challenge has been received. We've done it a few times, so we know the drill."

Earlier on Wednesday, the Herald reported that Team New Zealand are understood to be considering a radical proposal for the next America's Cup defence - a one-off defence against Ineos Team UK excluding other challengers on the Isle of Wight next year.

That would return to the Cup to its original home, where the Americans won the first regatta back in 1851.