Westgate Las Vegas SuperBook installed Spieth at 8-1 to win the title (and take home the career Grand Slam), along with Rory McIlroy?at the same odds.
Spieth had a 3-shot lead entering the final round at Royal Birkdale in Lancashire, England, but lost it on a bizarre 13th hole in which he had to take an unplayable lie and hit a shot from the driving range. He finished the championship by going 5 under par in the final five holes.
Dustin Johnson opened at 10-1 to win the PGA Championship, with Rickie Fowler and Jason Day at 15-1.
U.S. Open champ Brooks Koepka is 25-1. Masters champion Sergio Garcia is also 25-1.
The PGA Championship will take place Aug. 10-13 at Quail Hollow Club in Charlotte, North Carolina.