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Phil Mickelson truly took the golf world by storm when he won the PGA Championship last month. With the U.S. Open set to get underway on Thursday, bettors are backing Mickelson in a big way as he aims for the career grand slam that's eluded him.

After opening with 85-1 odds to win the U.S. Open, Mickelson's odds have dipped down to 40-1 at William Hill Sportsbook. Out of the 147 golfers for whom William Hill has futures, only 13 golfers have lower odds of winning the major tournament than Mickelson.

"Mickelson is leading tickets by a landslide now and he's got the most money now too," William Hill Director of Trading Nick Bogdanovich said. "The liability is at seven figures and counting. You'd think the lower number on Mickelson would slow them down, but that hasn't been the case at all. I think this will end up going past the Tiger [Woods] number at the [2019] Masters."

Mickelson currently has secured 8% of the total number of tickets with William Hill. Collin Morikawa (22-1), who won the Masters in April, has 5% of total tickets. U.S. Open favorite Jon Rahm (10-1), Brooks Koepka (12-1), Xander Schauffele (15-1), and Jordan Speith (23-1) have received 4% of the total tickets. In terms of the total dollars wagered, Mickelson and Koepka make up 9% of the field. Rahm comes in at 8% while Schauffele makes up 7%.

One William Hill bettor did place a $2,100 wager on Mickelson to win the U.S. Open when the odds were at 85-1. If Mickelson were to win, the total payout would be $180,600.

It's certainly not a huge surprise to see bettors backing Mickelson given all the momentum he's gotten from winning the PGA Championship. In addition, the 2021 U.S. Open takes place at Torrey Pines in La Jolla, California, which is where Mickelson lives. That definitely could give Mickelson a home-field advantage of sorts.

Who will win the U.S. Open, and which long shots will stun the golfing world? Visit SportsLine to see the projected leaderboard, all from the model that's nailed six golf majors and is up well over $9,000 since the restart.