Still just 22, and having already won a Premiership and played on a British Lions tour, the Harlequins star’s ascension continues when he faces the Wallabies at Twickenham this evening.
Much has been written about Smith’s meteoric rise and – having started in wins over the United States and Canada in the summer and off the bench versus Tonga last week – this will clearly be his biggest examination yet.
Moreover, Eddie Jones has, of course, picked his captain Owen Farrell at inside centre to facilitate Smith’s inclusion: that shows how much faith the England coach has in him.
However, for those who know the gifted player well, it is no surprise.
Leeds Rhinos assistant coach Sean Long, one of the best half-backs of his generation in rugby league, witnessed first-hand Smith’s development.
He spent 15 months as Harlequins backs coach before moving to Headingley last autumn.
Long told The Yorkshire Post: “Marcus was an absolute joy for me to work with.
“What impressed me the most about him is work ethic.
“Marcus was always wanting to learn.
“We videoed training and he watched back every session and would come in afterwards asking ‘what can I do there?’
“He was always asking questions whether it be what he should do against an aggressive defence or what his options were in other situations.
“He was the first one in and last one to leave. We’d go through things together after we’d trained.
“How much he wanted to improve was the first thing I noticed about him whether on his goal-kicking, kicking out of hand or when getting some lads together as he wanted to work on his short passing game with two v ones.
“I was blown away by his professionalism.”
Dazed opponents have been blown away by his pace and it will be intriguing to see if Smith - who replaces George Furbank as the starting 10 - finds much open space against the Wallabies.
But Long, 45, believes he now has the all-round game to excel at international level – and forge his own style.
“Marcus’ skillset was unbelievable. His catch, pass, ability to play off both feet and to fire a 20m cut-out without even loading it up; normally a player catches and has two steps before passing but Marcus does it all within half of that initial first step,” he recalled.
“He kind of wanted to play a little bit like Danny Cipriani and I said ‘look mate, you’re Marcus Smith; you can do things he can’t do.’
“Marcus is more of a runner but he can play, play square, he can beat people so my message to him was just to be Marcus Smith.
“When I first went down to Quins, he was always trying to run, run, run so I asked him to use his forwards around him more to line them up and look like he’s going to roll it before going through himself.
“But now he’s come into his own with his game-management as he did struggle with that initially given he always wanted to run or play from deep.
“Now he’s got a real good balance and you have to when playing for England.
“Marcus is understanding the game a lot more now and knows when to put it into a corner. He’s a brave lad, too. He’s only small but he gets his body in to tackle.”
Long is excited by the prospect of seeing Smith and Farrell - the 30-year-old who missed the Tonga game due to a ‘false positive’ Covid result - in unison.
“They should compliment each other and bring the best out of each other,” he said.
“They have really good communication as a 10 and 12
“He’ll already be learning off Faz and his game-management.
“Putting Marcus on the bench initially was a real good decision by Eddie (Jones).
“But, going forward, I think he can nail down that 10 shirt for the next eight to ten years.”
With George Ford overlooked for the autumn internationals, Smith has his chance to shine.
England attack coach Martin Gleeson - the former Huddersfield Giants centre who played alongside Long for St Helens, Hull FC and Great Britain – has been charged with bringing more creativity to Jones’ side before the 2023 World Cup.
Long believes he will help Smith flourish and said: “I speak with Gleese every day.
“Marcus knows my terminology because I come from league and I always say ‘turn the corner, turn the corner, play square’ and Gleese does the same. That helps.
“Gleese thinks he’s like a sponge; he says anything he tells him, Marcus does it and that he is highly-rated by all the coaching staff at England.”
England have won all seven games against Australia during Jones’ reign, most recently with a 40-16 success in the 2019 World Cup quarter-finals, while the Wallabies arrive having lost 15-13 against Scotland on Sunday.