Jordan Spieth gave himself a boost on the eve of the 144th Open by claiming a play-off victory over Tom Gillis at the John Deere Classic.
The 21-year-old, who will be seeking his third major title of the year at St Andrews, carded a three-under 68 to join 46-year-old Gillis, chasing a maiden PGA Tour title, on 20 under for the tournament.
The pair could not be separated when they played the 18th hole for the first time in the play-off, but Gillis drove into the rough second time around and then hit his second shot into water, enabling Spieth to wrap up victory with a three-foot putt.
Spieth, holding a two-shot overnight lead, got off to a slow start by bogeying two of the first three holes and found himself three off the pace with seven to play after being unable to save par from 20 feet at the 11th.
However, just like the world No 2 did in his third round 61, Spieth responded by carding a series of birdies on the back nine, drilling in lengthy putts at the 13th and 16th to go alongside closer gains at the 14th and 17th to move back in to a share of the lead.
Victory silenced Spieth's critics who felt the Masters and US Open champion should have been playing in Scotland this week, rather than stay loyal to the event which gave him his first professional victory.
Spieth made it clear that he had no regrets about opting to stay in the United States, saying: "I committed to this event well ahead of time, and it never really crossed my mind to drop out.
"I felt like I've played well in the Open Championship the last couple years having played at the John Deere right before and competed. When I get over there, whether I play well or don't play well has nothing to do with what I did the week before.
"I will certainly have enough energy. I will certainly have enough rest, and I will be as prepared as can be, as I am for any other event, by the time I tee it up at St. Andrews. I'm not worried about any of that."
Gillis, who was attempting to become the oldest first-time winner on the PGA Tour in 20 years, posted six birdies in a front-nine 30 and added three more after reaching the turn before a two-putt bogey from eight feet at the 16th.
Zach Johnson and last week's Greenbrier Classic winner Danny Lee finished a shot further back on 19 under after final rounds of 65 and 67 respectively.
Johnson was an unfortunate victim of an incident at the 16th hole, where he was noticeably startled by a loud blast just as he was about to putt, which appeared to come from a boat on an adjacent river.
The American took a drink of water and settled himself down but missed the birdie putt, before leaving a 15-footer at the last to earn a place in the play-off just short.
Chris Stroud, Johnson Wagner and Justin Thomas finished in a three-way tie for fifth place, with Steve Wheatcroft posting a back-nine 31 to join the group a further two strokes back.