The stunning betting estimates that Walters provides — from his own detailed record from what he describes as two reliable sources — are detailed in an excerpt of his book, “Gambler: Secrets from a Life of Risk.”

Mickelson’s management group did not immediately respond to an email from The Associated Press seeking comment.

Walters, widely regarded as America’s most famous gambler, said he ended his betting partnership with Mickelson in 2014. Two years later, Mickelson was a relief defendant in Walters’ insider trading case.

Mickelson was never charged and had to repay about $US1 million ($A1.5 million) he made off a stock deal.

Walters was convicted and sentenced to five years in prison. He said he could have avoided prison if Mickelson had told a “simple truth.”

Walters said he never told Mickelson he had inside information on Dean Foods stock.

“All Phil had to do was publicly say it. He refused,” Walters wrote.

“The outcome cost me my freedom, tens of millions of dollars and a heartbreak I still struggle with daily. While I was in prison, my daughter committed suicide — I still believe I could have saved her if I’d been on the outside.”

Walters said Mickelson told him he had two offshore accounts, and that Mickelson had limits of $US400,000 on college games and $US400,000 on the NFL.

He said, based on his detailed record and additional records provided by sources, Mickelson’s gambling between 2010 and 2014 included:

— Betting $110,000 to win $100,000 on 1,115 occasions, and betting $220,000 to win $200,000 on 858 occasions. That alone comes out to just over $US311 million ($A474 million).

— Mickelson in 2011 made 3154 bets for the year and on one day (June 22) he placed 43 bets on Major League Baseball games that resulted in $US143,500 ($A219,000) in losses.

— He placed 7065 bets on football, basketball and baseball.

“Based on our relationship and what I’ve since learned from others, Phil’s gambling losses approached not $US40 million ($A61 million) as has been previously reported, but much closer to $US100 million ($A153 million).

“In all, he wagered a total of more than $US1 billion ($A1.5 billion) during the past three decades,” Walters wrote.

Most stunning to Walters, he writes in the excerpt, was a phone call from the Ryder Cup in 2012 at Medinah.

He said Mickelson was so confident he asked Walters to bet $400,000 for him on the U.S. winning.

“I could not believe what I was hearing,” Walters wrote.

“‘Have you lost your (expletive) mind?’ I told him, ‘Don’t you remember what happened to Pete Rose?’ The former Cincinnati Reds manager was banned from baseball for betting on his own team. ‘You’re seen as a modern-day Arnold Palmer,’ I added. ‘You’d risk all that for this?’ I want no part of it.”

He said Mickelson replied, “Alright, alright.”

“I have no idea whether Phil placed the bet elsewhere. Hopefully, he came to his senses,” Walters wrote.

Europe rallied from a 10-6 deficit on Sunday, staging the greatest comeback by a visiting team.