Phil Mickelson will celebrate his 51st birthday one day before play begins in the 2021 U.S. Open at Torrey Pines - South in La Jolla, California, on June 17.

Mickelson needs the U.S Open to complete his career Grand Slam win. He’s finished second or tied for second in golf’s national championship a stunning six times.

With his brother Tim on the bag and Father Time unable to get inside the ropes, Mickelson became the oldest man ever to win a major with his victory in the PGA Championship Sunday. Following his record-breaking win, Mickelson's US Open odds moved from +12500 to +5000 although many golf betting sites continue to favor a group of younger stars, including Dustin Johnson and Kopeka, who was nursing an ailing knee at the PGA Championship.

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Lefty has played in 29 U.S. Opens, including entries as an amateur. He grew up in San Diego and has won the Farmers Open at Torrey Pines near San Diego three times – in 1993, 2000 and 2001.

However, as of Monday at BetMGM, Johnson and Koepka remain the frontrunners.

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Mickelson was as high as +42500 to win his sixth major title during play at Ocean Course at Kiawah Island before closing out a pouty Brooks Koepka and Louis Oosthuizen by two shots.

When play began Sunday, Lefty was +275 to win at DraftKings, after being +30000 on the same site on Wednesday.

Mickelson’s victory was an inspiration for anyone hoping to score a significant accomplishment later in life. His pal Tom Brady, who won a Super Bowl at age 43 in February, was among those offering congratulations on social media.

That’s my quarterback!!! LFG @PhilMickelson!! https://t.co/VkfoZY1mDw

— Tom Brady (@TomBrady) May 23, 2021

Oddsmakers, too, may have cheered the outcome even if several top sportsbooks suffered liabilities on the outcome deep into six figures.

“The result dinged us pretty good. The PGA Championship proved to be our most bet golf event ever,” said Patrick Eichner of PointsBet. “Phil entered as a top five liability before moving to a top three liability by the conclusion of day one — needless to say, some bettors did very well for showing faith in Phil.”

The handle laid on majors continues to climb, coinciding with the growth of legal sports betting. The 2021 Masters was the most-bet golf tournament ever at PointsBet – and several other sports betting sites.

At the Borgata in Atlantic City, exposure to Mickelson on the outright-win market was limited, so his win was welcomed but not costly.

"We had no liability on him throughout the tournament," said Borgata Race and Sports Director Thomas Gable. "We actually ended up doing well for the outright winner."

"We’ve already taken some action on Mickelson and he actually has the third most amount of money wagered on him here behind DeChambeau and Justin Thomas. I’d expect more people to put down some money on him before we get to Torrey Pines. He’s one of the most beloved players, and him winning the PGA will just give people some more motivation to back him," Gable said. "If he is able to pull it off, it would be the biggest story in sports for 2021."

Mickelson plans to play Torrey Pines in preparation for the U.S. Open before teeing off three weeks from Thursday as the most-recent major champion.

“If I stay sharp mentally, I can play well at Torrey Pines. I’ll take two weeks off before that. I’ll go out to Torrey and spend time on the greens and really try to be sharp for that week because I know that I’m playing well this could very well be my last really good opportunity to win a U.S. Open. So I am going to put everything I have into it,” Mickelson said in his post-PGA Championship press conference.

And absent from the stage both this past weekend and next month at Torrey Pines will be Lefty’s other long-time nemesis – besides himself – as Tiger Woods continues to recover from a single-car crash that occurred in Ranchos Palos Verdes, Calif., on Feb. 23.

Mickelson had been granted an exemption from the USGA to play in the U.S. Open this year to make another try at the career Grand Slam. It’s a pass he would no longer need after his win Sunday. The PGA Championship triumph pushed Mickelson up to No. 32 in the world and gave him a 2021 U.S. Open exemption.

Mickelson won the Masters three times - 2004, 2006 and 2010. His other majors besides Sunday came in the 2005 PGA Championship and 2013 Open Championship. In addition to Woods in 2002, Geoff Oglivy (2006), Lucas Glover (2009), Justin Rose (2009), Retief Goosen (2004) and Payne Stewart (1999) denied Mickelson a title with those six second-place U.S. Opens.

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