Here's the timeline on how the Queensland star famously won the day on the Old Course on Sunday by a single shot after the most brilliant comeback.

2.40pm: Smith and Cameron Young, both four shots adrift of Rory McIlroy and Viktor Hovland, set out on their pursuit on the Old Course in the penultimate group of the final round.

3.02pm: It doesn't take Smith long to strike, hitting his approach to the second to eight feet and sinking the birdie.

3.39pm: Hovland three putts the fourth from almost 80 feet, leaving McIlroy in the outright lead on 16 under.

3:46pm: Smith moves to 14 under with birdie on the fifth, two-putting from 88 feet.

3.56pm: McIlroy's in perfect control, a neat two-putt birdie at the fifth pushing him to 17 under, still three clear despite the Queenslander's strong start.

4.52pm: McIlroy just misses out on birdie on nine, but is left satisfied by enjoying a two-shot lead over Smith on the turn for home.

4.56pm: The most delicate of chips from 70 metres from the 10th flag finishes just five feet from the pin, setting up Smith for his first birdie in six holes. The start of a an incredible charge.

5.02pm: Smith begins to assert pressure, closing to within a shot by holing a second successive birdie from 16 feet at the 11th.

5.05pm: McIlroy finds the green with his drive at the par-4 10th, leaving his monster 126 feet eagle effort practically stone dead. Back to two ahead.

5.15pm: Smith is now relentless, landing a third consecutive birdie at the 12, holing from 11 feet to move to 17 under, within a shot of McIlroy's lead.

5.31pm: Suddenly, Smith's level after playing the 13th in superlative fashion, with an arrowed approach to 18 feet and a sweet putt.

5.40pm: He's in the lead after finding the vast green at the par-5 14th with a majestic second shot, Smith's dazzling near-90 metre eagle putt nearly drops. It only requires the shortest of putts for him to take the outright lead at 19 under.

5.58pm: After McIlroy shaves the hole with a birdie putt at 14, which would have brought him back level, Smith's run of birdies is finally ended. He gets a bit lucky with his drive ending in the hay on the 15th, but after a fine recovery, the knee-knocking, five-foot par putt he holes is every bit as crucial as the previous five birdies in a row.

6.11pm: After a safe par at 16 and recognising McIlroy's making no headway, Smith hits a courageous tee shot at the feared Road Hole 17th, splitting the fairway.

6.24pm: But Smith screws his approach to the 17th green, leaving his approach some 60 metres short. He has to putt by plotting a path around a bunker but still leaves himself facing a 10-footer for par. Imperturbably, he sinks it to maintain his one-shot lead going down 18.

6.26pm: Smith drives to the edge of the par-four 18th, leaving himself an awkward undulating eagle putt from 25 metres.

6.29pm: It's not over yet as McIlroy plays a majestic approach from 160 yards at the Road Hole to give himself a makeable birdie putt - but he misses, to the groans of the galleries.

6.31pm: Smith's first putt on 18 is a majestic effort, rolling up to just two feet away.

6.32pm: But wait! Out of the blue, an incredible eagle two at the last from Cameron Young, who holes from 17 feet, puts him level with Smith momentarily at 19 under.

6.33pm: But Smith makes no mistake with his historic short putt from two foot - the shot that's going to win him the Open at an incredible 20 under after a glorious eight-birdie, bogey-free final round 64.

6.35: The last-chance saloon for McIlroy. He needs an eagle to tie - but finishes well short of the green, doesn't threaten the hole and ends with a par to finish two shots behind in third place. Smith is the deserved champion.

Australian Associated Press