Grant Dalton warned Jimmy Spithill to watch his words in order to maintain the strong relationship between Emirates Team New Zealand and Luna Rossa.
Former Oracle Team USA skipper Spithill, who has competed in the America's Cup since 2000, was officially named as a new member of Luna Rossa overnight.
Spithill was at the helm of Luna Rossa's Louis Vuitton Cup loss to Team New Zealand in the 2007 America's Cup, before he made the switch to join Oracle Team USA where he won the event in 2010 and 2013.
But Dalton said the addition of thier rival to Luna Rossa wouldn't affect Team New Zealand's relationship with the Italian syndicate, provided he "kept his gob shut".
"The relationship between us and them won't falter via that he keeps his gob shut basically! But I think they will have that in control," Dalton told Radio Sport.
"We have a really strong relationship with Luna Rossa and it goes back in history now, and particularly now with them as challenger of record for the next Cup, that relationship has only got stronger."
In light of Spithill's move, Oracle's potential to compete in the 2021 regatta has become increasingly unlikely.
Yachting commentator Peter Lester said that Spithill's decision to jump ship has "significantly singled the end of Oracle".
"It really signals the end of Oracle for this next America's Cup," Lester said.
"It's been pretty well flagged out there that Oracle will not be back, but with Spithill walking and changing teams, I'd say that that's the end of Oracle."
However, Lester said Spithill, along with his extensive America's Cup knowledge, would be a good asset to the Italian syndicate.
"I think he brings a lot to the table," Lester said.
"I think it's a good signing by Luna Rossa because you're buying in a hell of a lot of knowledge in terms of how the America's Cup game is played."
"Luna Rossa are looking pretty strong in terms of people."