Michael Kim shot a final-round 66 to win the John Deere Classic by a eight strokes, pick up his first victory on the PGA Tour and qualify for the British Open at Carnoustie, which starts on Thursday.
Australian Matt Jones, who started the day third, was the only player to finish in the top 20 to shoot over par on Sunday.
After a birdie on his opening hole, the Sydney native dropped a shot at the third, made double bogey on the seventh and bogey on the ninth to slip out of the top 10.
His back nine included birdies on the two par-5s as he ended his week with a one-over 72 to be 15 under and tied for 12th.
Kim, who turned 25 on Saturday, shot four rounds in the 60s to finish at 27-under 257 - breaking Steve Stricker's tournament record from 2010 by one shot.
The South-Korean born American - who led by five shots after three rounds -took all the drama out of the final round with birdies on his first three holes on his way to securing the largest margin of victory during the tournament's stay at TPC Deere Run, which began in 2000.
Italian Francesco Molinari (64) and Americans Joel Dahmen (65), Sam Ryder (66) and Bronson Burgoon (69) tied for second at 19 under.
Australian veterans John Senden (68) and Stuart Appleby (67) finished tied for 34th and 50th respectively.