After turning down Phil Mickelson's request to place a $400 000 bet on the United States' Ryder Cup team, Billy Walters said earlier this week that he has no reason to believe the golfer resorted elsewhere to place the wager.

Walters, speaking on the "No Laying Up" podcast on Thursday, said he was stunned when Mickelson called him in 2012 and asked to throw a six-figure bet on the Ryder Cup at Medinah.

"I said, ‘Man, have you lost your mind?' Actually, I used a few explicit words," Walters said on the podcast. "And I said, ‘Don't you know what happened to Pete Rose?' I said, ‘You're going to be a modern-day Arnold Palmer.' I said, ‘Don't even – I don't want any part of it.'"

However, Walters believes Mickelson had a change of heart after that phone call.

"He said ‘Yeah, yeah, yeah.' And I'm fairly confident he came to his senses and he probably never made the bet," said Walters, a renowned sports bettor. "I didn't say he ever made the bet, I just said he called me and attempted to make the bet.

"He just probably got carried away with the moment, he was so sure they were going to win – but I don't think he was thinking when he called me. Because the ramifications, if I did that for him and it could have ever been proven, his career would have been over."

NEW BOOK

Walters wanted to clarify the excerpt about Mickelson and the bet from his upcoming new book, "Gambler: Secrets from a Life at Risk."

On 10 August, Mickelson took to social media to state that he never placed any wagers on the Ryder Cup. But he never denied calling Walters to inquire about the $400 000 bet.

"I never bet on the Ryder Cup," Mickelson said on Twitter. "While it is well known that I always enjoy a friendly wager on the course, I would never undermine the integrity of the game."

Walters said he wishes that Mickelson would come clean about the call.

"We're all cut out of a different cut of cloth, but I don't understand that," Walters said. "Instead of saying I never bet on golf, I know what I'd have said: ‘Look, I called. I was excited. It was a mistake, I never did it before, I never did it since.'"

Mickelson was part of the US Team at the 2012 Ryder Cup, but the Americans lost to Europe.