Final-round charges from defending champion Jordan Spieth and Jon Rahm proved in vain as Kevin Kisner claimed his second PGA Tour victory at the Dean & DeLuca Invitational.
Spieth was looking to become the first man to retain the title at Colonial since the great Ben Hogan in 1953 and performed admirably on Sunday, a bogey-free 65 lifting him to nine under for the tournament.
That aggregate score was matched by a typically pumped-up Rahm, whose closing 66 could have been even better if not for a number of agonising near-misses on the greens, and Sean O'Hair (66).
However, Kisner held his nerve to finish top of the pile, rounding off his own 66 with a superb two-putt from off the back of the 18th green as playing partner Rahm failed to convert an accurate approach into a birdie that would have forced a play-off.
After successive missed cuts and a poor start to this event, Spieth could at least take heart from his encouraging form over the weekend. He surged into contention with birdies at the first, second and fifth on Sunday, before picking up further shots at 10 and 15.
A scrambled four at the last kept Spieth in the hunt for glory, but Kisner was in no mood to give up the advantage he had seized with three successive birdies at the start of the back nine.
Although he followed another gain at 15 with a sloppy bogey at the next, Kisner remained in front - his gutsy par on 18 coming after a blocked drive had left him with work to do.
Rahm did his best to force extra time, a spectacular approach from behind a tree setting up a birdie at 17 before he threatened another on the final hole.
The Spaniard's putt did not drop, though, and Kisner was assured of victory when overnight leader Webb Simpson, needing a birdie to tie first place, finished with a bogey to complete a disappointing 71.
Veteran Steve Stricker recorded the best round of the week, a seven-under 63, to share seventh at six under, as Danny Lee (70) and Paul Casey (73) dropped out of contention.