Editors note: An earlier version of this story incorrectly used the word “refuting” when describing Phil Mickelson’s response to Billy Walters’ story that Mickelson wanted to bet on the 2012 Ryder Cup.

When an excerpt from American sports bettor Billy Walters’ upcoming book dropped Thursday morning, offering detailed allegations about Phil Mickelson‘s gambling habits, the six-time major winner was playing a pro-am at the LIV Golf event at Bedminster.

Lefty declined to comment when he finished the pro-am, but later released a statement to Golf Digest refuting Walters’ claims. Chief among them was an instance where Walters says Mickelson asked him to bet $400,000 on the American team to win the 2012 Ryder Cup, an event that Mickelson was playing in. Walters said he wouldn’t make the bet given the potential ramifications it might have for Mickelson, but that he had no idea whether Mickelson placed the bet elsewhere.

Mickelson played in a record 12 Ryder Cups for the United States, owning an 18-22-7 record.

“I never bet on the Ryder Cup,” Mickelson wrote in a statement sent to Golf Digest. “While it is well known that I always enjoy a friendly wager on the course, I would never undermine the integrity of the game.

“I have also been very open about my gambling addiction. I have previously conveyed my remorse, took responsibility, have gotten help, have been fully committed to therapy that has positively impacted me and I feel good about where I am now.”

The original excerpt came from an autobiography Walters has written called Gambler: Secrets from a Life at Risk, set for release August 22 and published by Simon & Schuster. Walters also outlined the gambling partnership he says he had for several years with Mickelson. Among Walters’ claims are that Mickelson wagered more than $1 billion during the past three decades and accumulated losses of close to $100 million.