A glance at the list of most balls faced in this series reveals no surprises at the very pinnacle. The top two positions are filled by the men ranked as the ICC's top two Test batsmen, though in reverse order: India's immovable rock, Cheteshwar Pujara, and Australia's adaptable captain, Steven Smith. But before the campaign began, few would have predicted Matt Renshaw would sit third.

A 20-year-old with no previous experience of cricket in India, Renshaw embarked on this trip with question marks over how he would handle the challenge of facing high-quality spin on turning surfaces. He was raised on the seaming pitches of Queensland and, even after scoring 184 against Pakistan at the SCG in January, was not viewed by Australia's selectors as a certain starter in India.

Most Test runs for Aus before the age of 21 538 - Matt Renshaw

482 - Clem Hill

472 - Phillip Hughes

468 - Don Bradman

410 - Doug Walters

406 - Stan McCabe

350 - Archie Jackson

299 - Neil Harvey

Yet Renshaw has occupied the crease for 567 deliveries in three Tests - more than Virat Kohli, M Vijay and David Warner combined - and has compiled 223 runs at 37.16. He has also surpassed the 119-year-old record set by Clem Hill in the 1890s for most Test runs scored for Australia before the age of 21: Phillip Hughes, Don Bradman, Doug Walters, Stan McCabe, Archie Jackson and Neil Harvey round out a high-class top eight on that list.

Although he is yet to turn one of his starts into a century on this Indian tour, Renshaw's patience and imperturbability have been key factors in Australia's competitive performances. His state coach at Queensland, former Test opener Phil Jaques, said he had been impressed - though not surprised - at the way Renshaw has prospered.

"He's able to implement a plan and not veer from that plan," Jaques told ESPNcricinfo. "Watching the series in India, I think he's done that really, really well ... I think he's structured his defence really well. He's worked hard on his defence and he's hitting the ball with the spin as much as he can.

"Those have been the big things with him. He's been incredibly patient and really waited for something that's in his area to score, and found a way of keeping the other stuff out. And if it does go past the edge, he hasn't been too bothered about it."

Matt Renshaw drives down the ground during his 108 Getty Images

This extreme level of patience was on display in December 2015, when at 19, Renshaw scored his maiden first-class century against New South Wales in Mackay. It was not your run-of-the-mill Sheffield Shield hundred: the pitch was slow, the outfield so glacial that bad balls were often bringing only singles or twos, and Renshaw finished with 170 from 395 balls in nearly nine hours.

"I'd seen glimpses of the way he could apply himself before that, but that was the one innings where I thought 'geez, this kid can bat time and apply himself'," Jaques said. "I think that's exactly what's been needed in India. Watching from the outside it looks like every ball has been a challenge. Every ball is like a new contest, a battle within a battle, and Matt looks like he's definitely been up for that.

"It's definitely rare [in such young players]. I've seen Matt face over 30 balls for zero, and he could have gone another 50 and not been bothered. That is a very, very rare quality to have, to not be bothered by a situation that's thrown at you. It's like water off a duck's back to him. It's pleasing to see that four-day mindset can be so prevalent in a young guy. He's definitely set himself up for success with that mindset."

One remarkable aspect of Renshaw's career is that although he has now played seven Tests and looks set for a long international future, he is yet to play even a single Twenty20 match at the elite level. Renshaw was not even signed to a BBL team last summer, and although that could change next season, the absence of short-form cricket early in his career has helped his natural patience to flourish.

"With the invention of T20 cricket and more one-day cricket being played, there's a need for players to have a lot more shots than they used to," Jaques said. "Being able to work out when to play those shots for different conditions is a skill, and it's probably a less important skill in the minds of some younger players now, in general. That's what I'm seeing from a coaching perspective.

"You've got to have shots, but you've got to know when to use them, and you've got to have the temperament to rein that game back in when the conditions aren't in your favour. That's something Matt does really well. He's got all the shots, but he knows when to choose them and use them ... He's definitely got all the shots to play those short forms of the game."

As for the long form, Jaques believes Renshaw's room for improvement could lie in gaining the confidence to play his shots more freely. Jaques, who himself played 11 Tests before a serious back injury curtailed his career, said the early signs were positive that Renshaw was already relaxing into international cricket.

"He's got a very clear plan of how he's going about it and it's bringing him success already now, but I think his strike-rate will definitely go up over time, the more confidence he gets in the environment," Jaques said. "There's a lot of distractions at that level, but he's taken them in his stride, and more importantly he's played with a smile on his face."