Harris English pipped Kramer Hickok to the Travelers Championship title after an incredible eight-hole playoff at TPC River Highlands in Connecticut.
Both had birdied the 18th hole in regulation to finish tied at the top on 13 under par, but it took another eight holes for another birdie to arrive as English holed from 15 feet to settle a marathon contest in fading light.
After both scrambled pars at the first extra hole, Hickok was convinced he had bagged his first win until his long birdie putt on the 18th green took a big lip-out, and English pulled off an extraordinary sand save from a horrible plugged lie in the front-right bunker.
Hickok's heart-rate would have rocketed on the 17th when his pitching wedge cleared the water by the narrowest of margins, with both racing their birdie putts six feet long before holing confident putts for pars.
They traded fours again back at 18 and Hickok gave himself another great opportunity to close it out when they returned to 17, knocking a sweet nine-iron to 10 feet only for the birdie putt to shave the left edge of the cup.
English again held his nerve to rattle in another clutch putt for par from seven feet to extend the contest back to the 18th, where both pulled their drives into the fairway bunker on the left, from where English clipped a delightful approach to six feet.
Hickok looked out of it when he got heavy-handed with his putt from the fringe and hammered it 15 feet long, but he nailed the return and breathed a huge sigh of relief when English's putt for the win lacked conviction and veered off to the right.
English was not able to capitalise on a venomous 357-yard drive as the seventh playoff hole (the 18th) was halved in routine pars, and both were lining up mid-range birdie putts with light fading as they played the 18th for the seventh time on the day.
But concerns over the finish spilling over to Monday were averted as Hickok two-putted for par, and English found the bottom of the cup with his aggressive 15-footer to secure his second PGA Tour victory of the season.
Several hours earlier, Bubba Watson had looked a firm favourite to equal Billy Casper's record haul of four wins in the event when he led by one with five holes to play, but his challenge unravelled as he closed with four bogeys and a double-bogey six at the 17th.
The left-hander cruised to the turn in three under and remained at 13 under for the tournament until he blocked his approach to the 14th and his putt from the run-off area barely made it to the green, and he then carved a long iron from the tee at 15 into the water.
His third almost rolled back into the hazard before a good pitch and putt saved a bogey, but he three-putted from 50 feet at the short 16th before his second from a fairway bunker on the penultimate hole came up short and found more water.
With Watson out of the running, Marc Leishman would have been confident of being part of a playoff after the Australian carded a superb bogey-free 64 which earned him the clubhouse lead on 12 under for just short of two hours.
English then birdied 13 and 16 to edge one ahead only to bogey the 17th, but he holed a brilliant birdie putt from just inside 30 feet on the final green to cap a 65 which left Hickok needing to match his closing three to force extra holes.
But after a clutch par save from six feet on the 17th green, Hickok flicked a wedge to eight feet at the last and got the putt to drop for a 67, with Leishman having left the practice range content with a podium finish.
Brooks Koepka also threatened to pull off an unlikely victory as he closed with a 65 to earn a top-five finish on 10 under along with Hank Lebioda, who was in the thick of contention after five birdies in an outward 30 before three bogeys in four holes after the turn ended his hopes.
Jason Day managed only two birdies in a frustrating 70 which left him at nine under and in a tie for 10th, one shot ahead of fellow Aussie Adam Scott (67) and in-form Italian Guido Migliozzi.