Steve Smith is on a journey to rediscover himself, and a tiny change ...

At 1:29pm in Brisbane, Steve Smith hit an on-drive.

The shot only earned him four runs, and was by no means the most spectacular of a day that was soon to be taken over by the swashbuckling Travis Head, but it was significant.

It came from the 91st ball Smith had faced in this innings and it took his score to 35. It may also have opened up a wormhole and sent the Gabba on a journey back in time.

For the time it took Smith to play that one stroke it was 2014 once more, and he was the most impossibly dominant player in the world again.

Impeccably balanced, Smith was still and composed and dripping with that 2010s aura as the ball erupted off his perfectly straight bat and sprinted to the long-on fence.

It was the return of an old friend, the first bars of a song you loved but hadn't heard for years, a season five Simpsons episode randomly being re-run.

A few years ago a stroke like that from Smith would have been entirely unremarkable, but halfway through day two at the Gabba it stood out in the midst of what was to that point a painfully scratchy knock.

Steve Smith was locked in from the outset, but took some time to get in a rhythm. (AP: Pat Hoelscher)

Steve Smith's struggles over the past 12 months have been well documented and will have frustrated nobody more than the man himself. There's also little he would not have tried to break out of that funk, tinkering with every element of his game to find the magic formula.

In Brisbane he arrived armed with a new plan — go back to the old plan.

From his first ball Smith had clearly re-implemented the dramatic trigger movement across his stumps that was a trademark in his most prolific years.

His exaggerated back-foot step into a semi-crouched position just as the bowler is about to release always seemed ungainly, but had the magic ability to transport the ball directly into the middle of his bat and with Smith miraculously in the perfect position for every stroke.

It was a way of activating whatever unique part of Smith's technique needed activating, and it was subject to subtle changes depending on the whims of the batter, as he was the only one blessed with a true understanding of it.

The first time Smith ever really put it to use in a Test match was against England at the WACA in 2013. He made a hundred that day, largely credited it to the adoption of the trigger movement and never looked back.

That was the day he became the real Steve Smith, plunderer of runs at an historic level and one of the most oddly elegant batters we've ever seen.

For more than a year now, and through an ill-fated experiment at the top of the order, that cricketer went missing. And so to rediscover the magic, Smith first had to rediscover the trigger that started it all.

As a nervy morning turned into a joyous afternoon at the Gabba, it was also clear what an incredibly positive influence Head was on Smith out in the middle.

Right now, Head is experiencing something as close as most players could hope to get to Smith at his peak. He is overflowing with confidence, positively fixed in his flow state and somehow able to play a cut shot to just about any delivery sent his way.

Travis Head played some typically outrageous shots in his incredible knock. (Getty Images: Cricket Australia/Matt Roberts)

The total freedom with which Head played was infectious and lifted Smith out of his own way and back into form.

You just have to laugh when you watch Travis Head bat at the moment. He is consistently playing strokes with the specific intent of making the bowlers as angry as possible.

Ramps over the keeper's head, slashing cut shots from the top of leg stumps, obscene clips over midwicket from Jasprit Bumrah's first delivery with the second new ball. No wonder Mohammed Siraj was so cranky in Adelaide; with every shot, Head thumbs his nose at Test cricket's dusty old conventions.

Head saluted his century with a smile and his now signature celebration — the helmet on the bat handle in a little nod to Aussie bowling coach Daniel Vettori — but Smith's came with a little more vigour.

After moving to 99 with an on-drive nearly identical to that which heralded his return, Smith clipped one to fine leg and strolled down the wicket and in the direction of his teammates to complete his run.

He took off his helmet, wiped his brow three times and held his bat aloft. He kissed the Australian crest and spun around to greet every corner of the Gabba.

And then, when facing his teammates in the stands again, he slashed his bat so hard he nearly whipped himself off his feet. After receiving a hug from Head, Smith turned back towards the Aussie camp with a glare and nodded his head.

Smith showed glimpses of his very best in making his 33rd Test century. (Getty Images: Cricket Australia/Albert Perez)

It was a release of his own pent-up anger, but also a message to everyone who has questioned him through this barren stretch — a message not undercut by his nicking off only one run later.

Smith had made his point. Who knows how many more of these days we will be treated to, so it's worth savouring every bit of it, but if you ask Smudge he'd likely tell you he could keep doing this for years.

Along with Head, Smith has set up this Test and this series gloriously, putting Australia in a position where, given the forecast, defeat in Brisbane seems unlikely.

There will be rain over the course of the next three days, to the point where any result other than a draw will be difficult. But if Australia's bowlers can take advantage of the windows they get around the weather then a first-innings total in excess of 350 might be enough to force a result.

That's for another day though. Sunday at the Gabba wasn't for sweating on results, but for getting lost in the thrill of some truly extraordinary batting.

Whether it's his last or the beginning of a late-career resurgence, it was special to watch Steve Smith at his best again, looking an awful lot like that hungry young 20-something cricketer about to master his craft and take the world by storm.