Walker, world-ranked 48 at the start of the tournament, shot a closing three-under-par 67 highlighted by back-to-back birdies at the 10th and 11th holes to complete a wire-to-wire victory, the first in the PGA Championship since Phil Mickelson at the same course in 2005.

THE RESPECT! Jimmy Walker and Jason Day hug it out. What a finish on SS4: https://t.co/H2f2lWxBfm https://t.co/S2GZ0z0ZGF

— Sky Sports Golf (@SkySportsGolf) July 31, 2016

Day, the 2015 winner, posted a 67 to claim second by three strokes from American Daniel Summerhays, who posted a 66 to finish third on 10 under par. Branden Grace of South Africa's 67 left him at nine under in a tie for fourth alongside US Ryder Cup hopeful Brooks Kopeka and Japan's Hideki Matsuyama.

Stenson closed with a 71 and shared seventh place at eight under with Germany's Martin Kaymer, who eagled the last hole for a 66, and 36-hole co-leader Robert Streb of the United States, while Ireland's Padraig Harrington took a share of 13th place after weekend scores of 65 and 68 for his highest finish in a major since 2012.

Walker, the Oklahoma-born resident of Texas, had started the day still not having begun his third round after heavy rain and lightning warnings had prevented play beyond 2:15pm on Saturday. Walker had a one-shot lead over world number one and defending champion Jason Day following his early Sunday morning 68 but looked to have gone off the boil as he went back out for his final 18 holes, missing birdie putts yet crucially not dropping shots.

He made the turn in level par but still in the lead as the expected chase from the field did not materialise. His round sparked to life at the par-four 10th and though his putter had not been his friend, Walker's sand wedge stepped up to the plate, the leader holing out from a greenside bunker to go to 12 under.

The huge roar from his gallery would have been heard by all his rivals and Day responded with a wonderful birdie putt one hole ahead, moving the Australian to 11 under but Walker pressed on, moving to 13 under at the 11th, this time with a much-needed long birdie putt.

Stenson had threatened the lead when his birdie at the sixth got the Swede to 10 under and raised the prospect of back to back majors for the 40-year-old but he failed to build any momentum and a double-bogey six at the 15th put paid to that.

It was up to Day to apply the pressure but he too failed to get his round firing having started with bogeys at the first and third holes. Three birdies got him going forward but with two holes remaining the Australian was still two shots adrift of the leader and although the l7th and 18th were both par-fives they had produced one birdie between them for the defending champion in previous rounds. He parred 17 but then produced some cheers of his own as he sent in his approach to the 18th green, setting up an eagle putt from 10 feet.

They were still ringing in Walker's ears at the 17th green when the American rolled in a birdie putt from inside 10 feet to deliver the ideal riposte, moving to 14 under and stretching his lead to three as Day prepared for his eagle chance.

The drama was not going to end there as Day sank the 10-footer with Walker watching from down the fairway, waiting to play his shot in.

It left Walker, now with a one-shot lead needing par to become champion but the pressure produced a wayward approach shot, the American finding rough to the right and below the green. His fate was still in his own hands, with three shots left to play with and the first of them lobbed the ball onto the green for a two-putt from 33 feet. His first cosied the ball to inside three feet from the hole and with Day watching from the back of the green in fading daylight, Walker rolled the par putt home and with a punch of the air, almost 12 hours after he had his first shot of the day, he was a major champion.