On-song Jordan Spieth gave himself a boost on the eve of the Open Championship with his fourth win of the year.
Spieth came out on top in a play-off with fellow American Tom Gillis to win the John Deere Classic at TPC Deere Run.
Spieth, who will be seeking his third major title of the year at St Andrews, carded a three under par final round of 68.
He was joined on 20 under par by 46-year-old Gillis, whose final round 64 included six birdies on the front nine.
The pair could not be separated when they played the 18th hole for the first time in the play-off – but second time around Gillis drove into the rough, then hit his second shot into water, enabling Spieth to wrap up victory with a three-foot putt.
It gave the 21-year-old his second victory in three years at the venue in Silvis, Illinois.
And yet it looked like Spieth, who went into the final round with a two-shot lead, may have been reined in as he started with two bogeys in his first three holes.
He said afterwards: “It was a really fun day and although I did not have the best start I’m certainly okay with the outcome.”
Zach Johnson and New Zealander 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. Just as he was about to putt he was noticeably startled by a loud blast, 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 putt and had to settle for par. The noise appeared to come from a boat on an adjacent river.
Johnson regained his composure and almost birdied the last hole, which would have earned him a place in the play-off. He finished with a six-under-par round of 65.
The American domination of the leaderboard continued as Chris Stroud, Johnson Wagner and Justin Thomas finished in a three-way tie for fifth place.