It's hard to imagine that Tiger Woods would have the most to prove when the PGA Championship gets underway next week at Valhalla Country Club in Louisville.
But that's the way it's working out.
His hopes to play in the FedEx Cup playoffs and be on the United States Ryder Cup team will depend on his performance at Valhalla, as well as how he does this week in the World Golf Championships-Bridgestone Invitational.
But there are others who have things to prove as well.
Rickie Fowler and Matt Kuchar, proving they can win a major; Phil Mickelson, proving he can put four good rounds together.
Check out the list of what some of the best names in the game have to prove at the PGA Championship.