South Korea's Lee Kyoung-hoon has claimed his first PGA Tour victory with a three-shot win as Ireland's Seamus Power saw his challenge fade at the AT&T Byron Nelson in Texas.
Power had started the final round well in contention after three fine rounds of golf left him four shots off the pace going into the last day of the tournament.
The Irish Olympian started the round well with two birdies on his first two holes before adding three more to make the turn at -5.
However on a day when scores were low all around him, Power suffered a bit of a collapse on the back nine as a double bogey on the 13th and a bogey on the 14th saw him lose ground and eventually sign for a round of 70.
Power finished the tournament on -18, seven shots behind winner Lee.
The 29-year-old Korean started his final round well, picking up five birdies on the front nine before a two-hour long rain delay added to the drama of the home stretch.
Lee stood firm when play resumed, closing out his tournament with birdies on the 17th and 18th to finish on 25 under - three clear of overnight leader Sam Burns.
The American saved his worst round for last, splitting two birdies with two bogeys on the front nine before picking up two late shots to card a two-under 70.
Power was one shot ahead of England's Luke Donald on 17-under, while Donald's compatriot Lee Westwood carded a four-under 68 to finish tied for 21st.
The Scottish duo of Russell Knox and Martin Laird rounded out the British contingent on 12-under and nine-under respectively.