"Somebody will sell out and go to it," Koepka said on Wednesday in the lead-up to this week's Honda Classic in Florida.

The four-time major champion's comments come after Monahan said he has "zero complacency" when it comes to the threat of the rival Tour – headed by Australian Greg Norman and his LIV Golf Investments.

"I told the players we're moving on and anyone on the fence needs to make a decision," Monahan said on Wednesday.

He also emphasised that players who sign up for any breakaway tour will lose their PGA Tour membership and should not expect to get it back.

"All this talk about the league and about money has been distracting to our players, our partners and most importantly our fans," Monahan said.

PGA Tour commissioner Jay Monahan delivered a strong message during a compulsory player meeting this week. PHOTO: Rob Carr/Getty Images.

"We're focused on legacy, not leverage.

"You saw it last week with Joaquin Niemann winning, receiving the trophy from a legend (tournament host Tiger Woods) who inspired him to take up the game.

"Those moments can't be replicated."

While a Tuesday meeting between Monahan and the players had been scheduled weeks in advance, it began just minutes after Phil Mickelson released a statement in which he apologised for his "reckless" remarks about the Saudi overtures.

The six-time major winner did not mention Monahan or the PGA Tour, which he referred to as a "dictatorship" in his explosive comments to Alan Shipnuck, whose biography on Mickelson is due in May.

Mickelson has said he and three other top players paid attorneys to write the operating agreement for a new league in which players would have more control.

Monahan declined to comment when asked if Mickelson had been suspended or faces punishment, citing the Tour's longstanding policy of not discussing discipline.

Norman's proposed league took a beating last week when top players including Jon Rahm and Rory McIlroy repeated their strong support for the PGA Tour.

In addition, Dustin Johnson and then Bryson DeChambeau – both often connected to the new league without ever having indicating which way they were leaning – then pledged their ongoing allegiance to the PGA Tour.

While McIlroy referred to the SGL as "dead in the water", Monahan was not so certain while former World No.4 Rickie Fowler said the concept isn't going away.

"There is zero complacency here," Monahan said.

"We will continue to talk to the players and continue to listen."

While Koepka has no interest in the rebel league and think most professionals are happy on the PGA Tour, he doesn't think that will stop the SGL leaders from pursuing players.

"Everyone talks about money. They've (SGL) got enough of it," Koepka said.

"They'll get their guys. Somebody will sell out and go to it."