Rory McIlroy took a dig at Phil Mickelson after the six-time major champion was forced to deny claims he tried to bet on a Ryder Cup while playing.
In an excerpt from the forthcoming book: "Gambler: Secrets from a Life at Risk," by Billy Walters, Walters recounted details of the bets he and Mickelson formerly made together.
The book says that Mickelson was so confident the United States would regain the Ryder Cup in 2012 that he asked Walters to bet $400,000 for him on that result.
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Walters declined and writes he had "no idea" if Mickelson made such a bet, one which would have lost as Europe recovered from 10-6 down to win by a point in one of the most memorable days in the event's history.
McIlroy was asked about the Mickelson claims after his opening round at the FedEx St Jude Championship, where he took a light-hearted swipe about the American's Ryder Cup future.
"At least he can bet on the Ryder Cup this year because he won't be a part of it," McIlroy said.
Mickelson: I never bet on the Ryder Cup
Mickelson initially declined to comment after his pro-am round ahead of the LIV Golf event in New Jersey, but later released a statement on social media.
"I never bet on the Ryder Cup," Mickelson said. "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."
Days before the first LIV event last year, Mickelson told Sports Illustrated that he was embarrassed by his "reckless" gambling but insisted his decision to join the Saudi-funded breakaway had nothing to do with financial difficulty.
"My family and I are and have been financially secure for some time," the six-time major winner said. "My gambling got to a point of being reckless and embarrassing. I had to address it. And I've been addressing it for a number of years. And for hundreds of hours of therapy.
"Gambling has been part of my life ever since I can remember, but about a decade ago is when I would say it became reckless. It isn't a threat to me or my financial security. It was just a number of poor decisions."
If you are affected by the topics in this article visit GamCare, the leading UK provider of free information, advice and support for anyone harmed by gambling.