Tiger Woods made a faltering start at the WGC Bridgestone Invitational as he finished his opening round on four over par, 10 strokes adrift from the lead.
Woods could only muster two birdies in his round of 74, which was ruined by six bogeys.
Priced at 25/1 to win the title, Woods is now in serious danger of losing his position as the world number one to either Phil Mickelson or Lee Westwood.
And while Mickelson has started strongly, the pace-setter is the somewhat unlikely figure of Bubba Watson.
Watson leads the field on six under par, and the left-handed American is priced at 12/1 to be crowned champion in Ohio.
Watson, who won his first PGA Tour title at the Travelers Championship in June, struck four successive birdies before his only bogey on the 15th hole.
Mickelson, the current world number two, is ominously placed in second place, just two shots behind the leader Watson.
If Mickelson wins, a place at the rankings’ summit is all but guaranteed. The American could also steal top spot if he secures a top-four finish in Ohio and Woods finishes outside the top 37.
Having already won a major this year at the Masters, Mickelson is in fine form, and he is now the 7/2 favourite to clinch the WGC Bridgestone Invitational title.
Englishman Westwood, meanwhile, can leapfrog Woods in the rankings if he wins in Ohio (he is 25/1 to do so) and Woods finishes outside the top two.
Who do you think will win the title? Rory McIlroy is two under par and he is priced at 14/1 to lift the trophy. See the full WGC Bridgestone Invitational Betting Odds market.