Smith emulated Jack Nicklaus's magical back-nine six-under-par 30 at the 1986 Masters to return the famous Claret Jug back to Australian hands for the first time in 29 years.

The 28-year-old seemed to be playing a support role to the main show when Rory McIlroy, with golf's biggest and most passionate galleries willing him to victory, when he reached the turn three shots behind the Northern Irishman on Sunday.

But the unflappable Queenslander hit the go button on the 10th hole to rattle in five successive birdies to snatch the lead – which he refused to relinquish – from McIlroy.

In winning, Smith became the first player since Nicklaus in 1978 to complete The Players Championship – considered by some to be golf's unofficial fifth major – and The Open double.

"It's not cocky; it's not arrogance; it's a belief in his game. He's such a competitor." - Sam Pinfold.

"Just shows his massive belief, his confidence," said Sam Pinfold, Smith's trusted Kiwi bagman.

"It's not cocky; it's not arrogance; it's a belief in his game. He's such a competitor.

"That's the Aussie Queenslander; think he drew a lot from that. He's never really pinned as a favourite or as one of the big dogs; and he loves to fight. Put him in a fight – three, four (shots) back – and he's going to step up his game and go for it.

"Just so proud of him. Deserves it; such a competitor. Just the attitude he's got, never gives up. So much guts. The whole back nine was just flawless."

Beneath the steely exterior, Smith said he could barely breathe down the stretch, trying to win golf's oldest championship on the sport's greatest stage and during its landmark 150th edition.

"These last four or five holes aren't easy around here, especially with the wind up off the left," he said.

"Just stuck to what I was doing. Yeah, just really proud of how I kind of knuckled down today and managed to get it done.

"To do it the way I did today was pretty cool to be back and really apply pressure, keep holing putts. Yeah, it was awesome."

Smith's breakthrough victory removed any chance of him being labelled as the best player without a major championship after finishing second at the 2020 Masters, third this year at Augusta National and fourth at the 2015 U.S. Open.

And the 28-year-old saluted in stylish, record-breaking fashion, equalling the lowest 72-hole winning score in major championship history.

Fellow Australian Jason Day set the 20-under-par record at the 2015 PGA Championship at Whistling Straits, before Henrik Stenson matched the score at the 2016 Open at Royal Troon and Dustin Johnson equalled it at the 2020 Masters to consign Smith to second.

"I knew it wasn't going to be too long before I got one of these," Smith said.

"I've knocked on the door, I think, maybe one too many times now. So it's nice to get it done."