Jordan Spieth found top gear when it mattered most to dramatically beat Matt Kuchar to victory in the 146th Open Championship, having earlier stuttered badly in one of the most extraordinary final rounds in the tournament's illustrious history.
At Royal Troon 12 months ago, Henrik Stenson edged out Phil Mickelson in a thrilling fourth-round duel that saw both men hit rare heights, the Swede carding 63 to secure the Claret Jug.
It was a very different story for much of Sunday at Royal Birkdale as Spieth, three clear of Kuchar overnight, turned in a largely abysmal performance for the first two-thirds of his round that evoked memories of his famous back-nine collapse in the 2016 Masters.
However, the Texan regained his form in the most sensational fashion upon rescuing an unlikely bogey on the 13th, where he ultimately took a drop from an unplayable lie on the nearby practice ground after his drive had landed in heavy rough to the right of the fairway.
Having done well to fall just one behind Kuchar, Spieth duly picked up five shots over the next four holes to regain control of the tournament - birdies at the 14th, 16th and 17th coming either side of a mammoth eagle putt finding its target at 15.
WHAT. A. PUTT. pic.twitter.com/9M7x1heOSY-- PGA TOUR (@PGATOUR) July 23, 2017
Spieth completed a round of 69 to finish on 12 under, once more three ahead of Kuchar, who could only rue a failure to fully capitalise on his rival's initial woes.
Li Haotong carded a 63 on the final day to finish third, six off the pace, with Rory McIlroy and Rafael Cabrera-Bello a shot further back.
Spieth will now head to next month's US PGA Championship at Quail Hollow with the chance to become only the sixth man in history - and the youngest - to complete golf's Grand Slam by winning all four majors.
Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus and Tiger Woods make up the current members of that elite club, with Woods achieving the feat almost seven months on from his 24th birthday. Spieth turns 24 on Thursday.
The 2017 Open champion is also the youngest winner of the event since the great Seve Ballesteros, who was 22 when he triumphed in 1979 at Royal Lytham & St Annes.
If Spieth's front nine performance, which saw him turn in 37 to Kuchar's 34 after bogeys at three of the first four holes, was unconvincing, the wheels certainly appeared to have come off when a wild drive at 13 prompted him to raise his hands to his head in despair.
Astonishing scenes followed, Spieth eventually taking a penalty drop in the most unusual of territory on the practice ground after prolonged deliberation with rules officials.
By the time Jordan and Kuch finish the 13th hole, everybody else on the course will be finished.-- Billy Horschel (@BillyHo_Golf) July 23, 2017
Yet he somehow found the strength to limit the damage and duly rose from the depths of despair to almost ace the 14th before converting a short birdie putt to regain a share of the lead.
If that represented an impressive regathering of composure, Spieth's next act was truly outrageous. An enormous eagle putt from the front of the 15th green bettered Kuchar's birdie from the sand and the long-time leader was suddenly back in control.
Further birdies followed at 16 and 17 as Spieth charged to the winning post, his outstanding performance over the closing holes all the more remarkable for the torturous struggles that preceded it.