Smith ended the tournament level with the card in a tie for 13th with fellow Australian Lucas Herbert, whose challenge faltered down the stretch.

Herbert made a spirited Sunday charge to give himself a glimmer of hope of catching Chilean leader Mito Pereira and snatching the Wanamaker Trophy.

He powered into a share of fifth place after reaching the turn in two-under-par for his round and three-under overall at Southern Hills Country Club.

Herbert birdied the opening hole and briefly pulled the margin back to five shots with a second birdie at the third after Pereira took bogey on the same hole.

But successive bogeys on holes 11 and 12, where he needed a penalty drop after an errant tee shot, marked the beginning of the end for Herbert.

Lucas Herbert signals to the crowd after making birdie at the 72nd hole. PHOTO: Ezra Shaw/Getty Images.

Another bogey on 14, followed by a double on 16 dropped Herbert to three-over before he rallied to finish with consecutive birdies in a round of 71 to share 13th with Smith.

Pereira ultimately blew his big chance to become the first Chilean to win a golf major, making a double bogey at the last hole to open the door for American Justin Thomas to clinch a second PGA Championship in dramatic fashion.

Thomas, who started the day seven shots off the pace and fell eight behind after six holes, closed with a three-under 67 to force a three-hole play-off with fellow American Will Zalatoris (73) after both finished at five-under.

Thomas birdied two of the three play-off holes to beat Zalatoris by a shot, adding the title to his 2017 PGA Championship triumph at Quail Hollow.

Of the other Australians to make the halfway cut, Marc Leishman closed with a two-under 68 to be tied 34th at four-over.

Cam Davis (70) shared 48th spot at six-over, with Jason Day (73) finishing in a tie for 55th at eight-over.