But now one of the biggest beneficiaries of his absence is looking to steal his thunder in more ways than one.
Labuschagne has grabbed his opportunity with both hands and even Smith thinks the Queenslander takes it to the next level.
After struggling to get to triple figures, the floodgates have opened this summer with Labuschagne hitting centuries in his past three Test innings as he builds his own legacy.
The 25-year-old is now the equal-fourth fastest Australian to 1000 runs behind Donald Bradman, Neil Harvey and Sid Barnes, equallinged 1920s batsman Herbie Collins, Doug Walters, Mark Taylor and Adam Voges at 18 innings.
He's also the first since Bradman in 1937-38 to score a hat-trick of centuries for Australia from number three and first since Arthur Morris in 1947 to score his first three tons in consecutive innings.
While Smith was looking rather uncomfortable with 43 off 164 balls before he was caught pulling down the leg side, Labuschagne was in his element, bringing up his century with a six.
Bizarrely, SEN's Simon Katich predicted the magical moment.
"He nearly brought up his hundred in Adelaide with a six over mid-off so I wonder whether that will be starting to enter his mind here to Santner," Katich said.
He'd barely been able to take a breath before Labuschagne crushed the Kiwi spinner down the ground for the maximum.
In a pre-taped segment on Channel 7, Smith said Labuschagne takes his perceived weirdness to the next level.
"A lot of people think that I'm very strange, I think he tops me personally," Smith said. "He's an incredibly strange individual but he's got some good talent, he's going to be a good player I think, but very strange."
But Dave Warner believes the pair are trying to outdo each other, which seems to be to all of Australia's benefit.
"I think they're trying to outdo each other, I think it's about who can get the most screen time," Warner said.
He also revealed his nickname "STS" for "Sillier Than Steve".
Then again, what's better than one Steve Smith …
But Australia are loving watching the star bat with a hunger for runs as big as Smith.
O'KEEFFE'S BIZARRE EYE THEORY
Aussie Test great Kerry O'Keeffe on Thursday evening delivered the weirdest explanation yet for how Labuschagne appeared so comfortable and rock solid against some of the best bowling attacks in the world.
"Marnus Labuschagne's eyes are interesting guys," O'Keeffe said in commentary for Fox Cricket.
"A mate of mine who studies eye position tells me his (Labuschagne's) eyes are so close together it's such an advantage. He suggests Roger Federer and Novak Djokovic … athletes who both have eyes very close together and I've looked at Marnus' and they're tight.
"Just a thought. It's a theory."
After a photo of Labuschagne was brought up on the telecast, Aussie legend Adam Gilchrist said of Labuschagne: "They look like beady little eyes looking back there".
WARNER'S SLEDGE IN FIERY CLASH
There is never any love lost in trans-Tasman matches and in the heat of Perth's Optus Stadium, the latest series started the same way.
While Marnus Labuschagne and Steve Smith took some of the heat out of the contest late in the day, the opening overs saw both teams fired up.
Just six overs in, Tim Southee took exception to a wicketless start throwing the ball back at Joe Burns and hitting him in the hand.
The fans weren't happy with boos ringing out around the stadium.
At the non striker's end, Warner, never one to back down from a fight, had a couple of words to say to the Kiwi opening bowler.
Warner said: "C'mon mate".
Southee then explained: "He (Burns) was out (of his crease)" — his heel was hovering over the crease.
Warner shot back: "But you hit his hand".
Southee shrugged it off: "Well he was in front of the wicket".
It only angered Warner more.
"C'mon, you're supposed to be Mr Nice Guys," Warner finished pointedly.
The Courier Mail's Robert Craddock called it "an unexpected icebreaker" especially following the ball tampering scandal after which Australia took a calmer response in the middle.
Speaking on Channel 7, former Aussie captain Ricky Ponting said it was clear from the heated exchange the battle will rage during this series.
"I tell you what the Aussies will notice, there was no apology, either," Ponting told Channel 7.
Kiwi legend Brendon McCullum defended Southee, by suggesting his throw slipped from his fingers and he didn't intend to strike Burns.
"I think it's gone horribly wrong, I think it's caught in his fingers," McCullum said.
"David Warner didn't miss him anyway."
Warner, who passed 500 runs for the summer during his innings, was dismissed just before lunch with Neil Wagner taking a screamer of a catch.
'WE'RE THE WORST': AUSSIE'S ALL-TIME HOWLER
It's rare that the cricket world focuses on umpires for any good reason, but Aleem Dar set an all-time record.
The umpire from Pakistan is now the most capped Test match umpire of all time, passing West Indian great Steve Bucknor with his 129th cap.
It was a good start but it didn't last too long as the umpire was dragged into what turned out to be a bad call with an LBW decision which only could have hit another stump down the leg side.
While Dave Warner was slapped on the wrist by the commentators for standing too wide at the nonstriker's end, the ball was missing by a long way and would have been hitting an extra leg stump.
When Burns needed some advice, he was left to fend for himself, worsening Australia's record with the review.
Mark Waugh admitted it looked pretty good but replays showed it missed by a long way.
"Not a great start for Aleem Dar though," Waugh said on Fox Cricket commentary. "It wasn't a shocking decision but I go back to the Ashes where Aleem Dar couldn't get one right."
Australian great Michael Hussey said it's something Australia needs to improve.
"I know it's been a big concern in the camp as well. Statistically we're the worst at it in the world," Hussey told foxsports.com.au.
"I think the process needs to be worked on. Who's involved in the process, try to minimise that as much as possible, and try not to get too emotional about it."
