Bryson DeChambeau threw away his chances of winning the WGC-FedEx St Jude Invitational with a costly triple-bogey six at the par-3 11th in the final round at TPC Southwind, on a day where Mexico's Abraham Ancer clinched his maiden PGA Tour title.
The big-hitting American held every chance of landing a first career WGC title when moving into a share of the lead early on in the front nine, but an uncharacteristic back nine of 41 shots saw him fall back into the pack and four shots out of a three-man playoff.
DeChambeau started the final round two shots off the pace but soon raced into a share of the lead following birdies at the 1st and 3rd holes.
He sandwiched a birdie on the 5th in between bogeys at the 4th and 6th to fall a shot back, but then picked up another birdie at the 9th to remain very much in contention for a ninth career PGA Tour title.
However, things took an immediate turn for the worse as DeChambeau drove into water on the 10th hole leading to a bogey-five, and he compounded that mistake by once again finding water with his tee shot on the tricky par-3 11th en route to a disastrous triple-bogey six.
That wasn't the worst score of the day there, however, as South Korea's Si Woo Kim recorded the highest-ever score on the hole in PGA Tour history with a 13.
DeChambeau steadied the ship with three consecutive pars but another bogey on the 15th ended any hopes of a fightback and he would go on to bogey the final hole (missing a four-foot putt for par) for a round of 4-over 74 to finish tied eighth on 12-under par.
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In similar fashion to DeChambeau, compatriot Harris English who led by as many as three shots early on in the back nine, also collapsed spectacularly coming home with two double-bogeys on both par-3 holes at 11 and 14.
English, who was playing alongside DeChambeau, then added to his problems with a bogey at the relatively easy par-5 16th and it meant he fell out of the lead for the first time all day.
While all that was going on, Hideki Matsuyama and Sam Burns were setting a clubhouse target of 16-under par following rounds of 63 and 64 respectively, and that score was soon matched by Mexico's Abraham Ancer, who carded a 68.
Cam Smith was also 16-under par playing the final hole but the Australian drove into trouble and ended up making a double-bogey six to fall back into a tie for fifth on 14-under par alongside Paul Casey and Daniel Berger.
English gave himself a 12-footer for birdie on the 18th hole to make it a four-man playoff, but he was not able to hole the putt and had to settle for solo fourth on 15-under par - a result that marks a third top-four finish in his last four appearances on the PGA Tour.
Ancer then went on to seal his maiden PGA Tour title with a birdie from six feet on the second extra hole. Matsuyama two-putted from 25 feet for a par, while Burns missed a short five-foot putt for birdie to force a third extra hole.
FINAL ROUND LEADERBOARD
-16* A Ancer (Mex), H Matsuyama (Jap), S Burns (US)
-15 H English (US)
-14 D Berger (US), P Casey (Eng), C Smith (Aus)
-12 B DeChambeau, W Zalatoris (US)
*Ancer wins with a birdie on the 2nd extra hole