Standing deep in the bowels of Soldier Field, it somehow seemed more fitting to have spoken with the star of the show here rather than in the regimented confines of a press conference room.
There wasn’t a mark on Larmour that suggested he had just played 80 minutes of Test rugby. Then again, the Italians barely laid a finger on him.
Instead, the fresh-faced 21-year-old looked as if he had just strolled confidently out of English paper two, relieved that his poet of choice came up.
While stood underneath the booming stands at the home of the Chicago Bears, the hulking figures of the Maori All Blacks ran passed en route to the pitch, while referee Nigel Owens sped by in the back of a golf cart.
In the middle of it all, a calm Larmour reflected on his latest mesmerising performance that further cemented his place as one of the world’s most exciting young talents.
Not that you would have known it from his demeanour however, and perhaps the most telling aspect of the ensuing conversation was the emphasis that Larmour placed on his shortcomings.
The Leinster flyer embodies the new breed of young players coming through in Ireland – confident in his ability, yet aware that he has a long way to go.
Just as the likes of James Ryan and Jacob Stockdale do, Larmour never second guesses his instinct.
For all the dazzling tries that he has scored since making his professional debut just last year, Larmour’s work around the pitch often gets overlooked.
He never shirks his defensive responsibilities and his reading of the game is improving, which is encouraging for someone who only sat his Leaving Cert two years ago.
Making mistakes is part of the learning curve and given that he has not made that many, Joe Schmidt’s decision to start him against Argentina this evening was made all the easier.
Even in his early school days, Larmour was bamboozling defenders in the same way that he is now doing on the international stage. The grainy footage of the 2014 Leinster Schools Senior Cup semi-final is worth digging out on YouTube as one such example.
As lethal as the former St Andrew’s College student’s footwork is, it is his innate ability to use it that is allowing him to carve open defences.
People will point to fact that last weekend was against a second-string Italian side, which is a fair point, but there are few players who could live with that side-step.
Looking back on the 14 tries that Larmour has scored in his 21 starts for club and country, the one common theme is how he has the utmost trust in his technique.
His ability to fix a defender by locking eyes, then instantly shifting the weight from his left foot to his right makes him a nightmare in a one-on-one situation.
Image 1 depicts that perfectly. He draws in (red line) Johan Meyer, whose body position is all wrong as Larmour steps off his left (yellow).
Even when he dances around the Italian flanker, there is so much work to be done. The way in which he arcs on a bending run (black) around another couple of tackles is something you can’t really teach.
Tadhg Beirne’s (blue) lazy run is also crucial here as it allows Larmour to run around his team-mate and into a gap that didn’t exist a second previously.
It is also worth pointing out Luke McGrath’s support line. You can just about see the scrum-half’s leg (green) behind an Italian.
It says a lot about the trust that he has in Larmour to make a line-break that he has already set off in support before the space has opened up. He was rewarded for that cleverness when Larmour put him over for a scintillating try.
Last season, Larmour had already produced magic moments before he lit up Thomond Park with a try for the ages.
Image 2 shows a similar scenario. Again, Larmour (yellow) fixes the defender (red), who in this case is Andrew Conway.
Sammy Arnold and Rory Scannell (the two in blue outside Conway) come flooding over in support, recognising the danger.
Rather than give the easy pass to James Lowe (green) on his outside, Larmour backs himself and runs another searing line (black) that beats five defenders.
It’s not just his footwork and pace that has seen Schmidt place his trust in him. He covers the back-field well, is good in the air and also has a big boot, which we saw to good effect in Soldier Field.
His role in helping see out the third Test victory in Australia last summer was vital. He injected a spark off the bench and his aerial take over Israel Folau (image 3) was not only world-class, but a real momentum-gainer.
Larmour gave up six inches to arguably the best aerial player in the world, yet still managed to win the duel, again because he trusted his technique by never taking his eyes (yellow) off the ball.
Asked about his footwork last weekend, Larmour quickly switched the focus back to an area of his game that needs to improve.
“I got caught against Toulouse one-on-one, so on the other side of the ball I need to get better, that is something I am working on.”
Pointing to an error by his own volition summed up his insatiable desire to succeed, even after a stellar, man-of-match-display.
Image 4 shows Leinster caught short on their right. Toulouse recognise it (red) with Selevasio Tolofua (green) carrying the ball into contact before offloading to Sofiane Guitoune (blue), who runs a Larmour-esque line (black).
In hindsight, Larmour (yellow) will feel that he should have come up into the line rather than remaining in the back-field. Instead, he gets caught in no man’s land and Guitoune dishes out a taste of his own medicine with a sensational step.
It was a rare error from Larmour, who is fast becoming the heir to Kearney’s full-back throne.
Given how dangerous Argentina are in their back-three, he can expect the Pumas to target him, but he won’t be fazed by that.
After all, this is a confident young player with the world at his dancing feet.