Phil accused of wanting to bet $400K on own Ryder Cup team in 2012

Warning: Story contains coarse language

Phil Mickelson's gambling habits are no secret, but an excerpt in Golf Digest from Billy Walters' upcoming book "Gambler: Secrets from a Life at Risk" reveals just how serious things got.

Walters, one of the most successful sports bettors of all time, formed a gambling partnership with Mickelson for five years up until the spring of 2014.

Walters claims he received a call from Mickelson in September 2012 while the latter was set to compete in the 39th Ryder Cup at Medinah Country Club. Mickelson was feeling extraordinarily confident that the U.S. team led by him and Tiger Woods could beat the European squad after losing in 2010. Walters says Mickelson asked him to place a $400,000 bet for him on the American team to win.

"Have you lost your fucking mind?" Walters remembers telling him. "Don't you remember what happened to Pete Rose? You're seen as a modern-day Arnold Palmer. You'd risk all that for this? I want no part of it."

"Alright, alright," Mickelson replied, according to Walters.

Walters says he has no idea if Mickelson placed the bet on his own accord, but he hopes he didn't. The Americans led 10-6 entering the final day of singles matches, but the Europeans stormed back to win in what's known as the "Miracle at Medinah." Mickelson lost his match to Justin Rose that day as part of the collapse.

Mickelson denied betting on the Ryder Cup in a statement posted on social media.

Based on the pair's relationship and what he's learned from other people, Walters claims that Mickelson's total gambling losses are likely much closer to $100 million and that he's wagered more than $1 billion over the last 30 years.

In addition, according to his own betting records and information from two sources, Walters said Mickelson placed 3,154 bets alone in 2011. On June 22 of that year, Mickelson placed 43 bets on MLB games, resulting in $143,500 in losses. The two sources also told Walters that Mickelson would routinely make single-game bets of $100,000 or $200,000 on football, basketball, and baseball.

Walters was convicted of insider trading in 2017. He served five years in federal prison and was fined $10 million, but he believes Mickelson could've prevented this by publicly sharing "a simple truth" he'd already told the FBI that Walters never told Mickelson he had inside information about stocks.

"All Phil had to do was publicly say it," Walters said. "He refused."

Walters' book comes out Aug. 23.