Mediate birdied his last two holes for a 6-under 64 at Minnehaha Country Club. He won after Duke, tied for the lead going into the final hole, caught two nasty lies in the rough and made double bogey.
Mediate wound up winning by two shots. "When I added them up, I went, 'Holy crap, 64.' That was cool," Mediate said. "It was just one of those days everything kind of went really good. When I was bad, I got it up-and-down. When I was good, I made putts. You have to do this crazy stuff. Putted my you-know-what off today, but I hit a lot of good shots, too. I hit a lot of green, kept my head together and here we are."
It was his first victory since the Senior PGA Championship in 2016. Duke had a share of the lead going into the final round for the first time in his career and held his own until the last hole. His drive took a hop to the right into the rough, leaving Duke a bad lie. From off the green, he sought relief because he thought the ball was in the lining of sod, but that wasn't the case.
It took him four shots to reach the green, and he missed the putt. His double bogey gave him a 69 and forced him to share second place with Colin Montgomerie and Bob Estes, who each had a 67. "I hit a good tee shot and it just kicked hard right into the rough a foot and I had a horrible lie," Duke said. "Then, I hit the shot up here and I thought it was in a seam of sod, but he said there was no sod, nothing sodded. It was probably one of the worst lies I've ever had sitting down. I mean, then what are you going to do after that? Nothing you can do about it. I played good. Thanks for all the people that came out and it was great to be here."
Jay Haas (66) and Steve Flesch (68) tied for fifth. Scott McCarron, who leads the Charles Schwab Cup, shot 67 with a bogey on the 18th and tied for seventh. Only two tournaments are left before the Schwab Cup playoffs, a series of three tournaments.