The Westgate SuperBook in Las Vegas has McIlroy as the favorite at 7-1, followed by Spieth at 8-1. McIlroy is also the favorite at European sportsbooks, but in Las Vegas, several shops had Spieth atop their odds, and a few made McIlroy and Spieth co-favorites this week at Quail Hollow Club in Charlotte, North Carolina.
While oddsmakers are divided on the favorite, the consensus is that McIlroy and Spieth have separated themselves from the pack. They are only golfers with single-digit odds. Dustin Johnson, Rickie Fowler and Hideki Matsuyama are in the next tier of contenders, each listed at 12-1 at the Westgate. U.S. Open champion Brooks Koepka is 20-1, while Jon Rahm and Jason Day are 25-1.
The Westgate initially opened Spieth and McIlroy as co-favorites at 8-1, shortly after Spieth won The Open in July. They were both sitting at 7-1 last weekend, when Westgate oddsmaker Jeff Sherman noted Spieth's somewhat erratic play at the World Golf Championship-Bridgestone Invitational and decided to inch his odds back a little bit, making McIlroy the favorite. Spieth was attracting the most bets and money at most Las Vegas sportsbooks, though. More money has been bet on Spieth to win the tournament than any other golfer, by a wide margin, at William Hill's sportsbook. He was also top golfer in tickets and money at Westgate.
"Spieth is going to get a lot more betting support in the U.S. markets, while McIlroy is going to get more support in the European markets, when the odds are this close," Sherman said.
McIlroy is a -150 favorite to beat Spieth head-to-head this week. McIlroy has two previous wins at Quail Hollow. Spieth needs a win at the PGA Championship to complete the career grand slam. Spieth is the favorite at MGM's sportsbook and, as of Tuesday morning, had attracted 30 percent more bets and 50 percent more money than McIlroy, according to assistant manager Jeff Stoneback.
The largest bets on the tournament at MGM, though, weren't on Spieth or McIlroy. Stoneback said a casino player bet $10,000 on Daniel Berger at 25-1, $6,250 on Charley Hoffman at 40-1 and $5,000 on Zach Johnson at 50-1. Each bet would net $250,000.