By the close, India had reached 219 for 7 in their first innings, still trailing by a sizeable 134 runs with only the wicketkeeper Dhruv Jurel remaining of their recognised batters. And on a surface that is already offering significant variable bounce, Root recognises that any lead could be crucial going into the back-end of the contest.

"We've got ourselves into a nice position at the end of the first innings," Root said at the close of play. "So we'll see how things progress throughout the game. Obviously, it looks like it's going to keep deteriorating and keep getting worse. So if we can get three early wickets tomorrow, hopefully that puts us in a really strong position for the rest of the game."

Already, however, Root's unbeaten 122 from 274 balls looks like being the stand-out innings of the game. After rescuing England from a dicey 112 for 5 at lunch on day one, he helped add a further 51 runs for the final three wickets in the morning session, and admitted it had been a cathartic display after his struggles for form in the opening three Tests.

"That's how I try and play every game really," he said. "Trying to play the conditions, the situation of the game. And it was very, very obvious what was needed in that situation on that surface. And thankfully, it paid off.

"It's been nice to contribute this week," he added, having managed a top score of 29 in his previous six innings in Hyderabad, Visakhapatnam and Rajkot. "It has been a lean series for me. So I was desperate to try and get some runs for the guys, and it was nice to do that today. And hopefully that can continue that for the rest of the series now."

Root had been the subject of intense scrutiny after England's 434-run loss in the third Test, after falling to his trademark reverse-scoop early on the third day, a shot that proved the catalyst in his team's subsequent collapse. And though the stroke didn't feature at all in the course of his century, he did joke that he had been tempted to unfurl it when in sight of his hundred on the first evening.

"I must admit it did briefly cross my mind, but on that wicket it's not a great option," Root said. "It was a fleeting and selfish thought that left my mind very quickly. If you look at the previous wicket [in Rajkot], it wasn't as bad, but it was unfortunate it kept a little bit low. But that's how it goes sometimes."

When asked afterwards about the criticism of that dismissal, Root added: "Certainly the execution of the shots has weighed on me. Not necessarily the selection but the execution. I'm better than that. Batting is about outscoring the opposition, scoring more runs to give yourselves the best chance of winning. If you get out, you're out, and it doesn't matter what it looks like."

Instead, Root delivered a performance of old-school hard graft, as he first found a means to survive a tough morning spell from the debutant Akash Deep, who extracted significant seam movement with the new ball, and then led a critical rebuild as the conditions eased, particularly alongside Ben Foakes on the first afternoon and Ollie Robinson on the second morning.

"If it's your main skill, you want to be delivering and you want to be standing up and performing," Root said. "It was special, given that in the morning the wicket was doing all sorts against that hard ball. So when you went in, you really had to work hard, in the first half-hour especially. They're the ones that mean most, when you have to really work hard for it, and you're trying to dig your team out of a little bit of a situation."

The second day, however, was dominated by Bashir's outstanding display with the ball. He bowled 32 overs, interrupted only by intervals and a solitary change of ends before the close of play, to return figures of 4 for 84, which are already his best figures in all first-class cricket. With Tom Hartley also impressing with two wickets in his 19 overs, it meant Root - England's most experienced spinner - was used for just a single over at the end of the day, but he had no complaints about ceding the stage.

"The way the guys have operated today was a brilliant effort," he said. "I had a great view at first slip, watching them operate. For two young spinners to stand up and perform, it's really encouraging for English cricket, and for us, for the rest of this series and the rest of this Test match."

Bashir was a virtual unknown when he was drafted into the squad in December, on the strength of only a handful of fixtures for Somerset, including a key spell against Essex in which his high release point was shown to have troubled Alastair Cook, one of England's greatest players of subcontinent-style spin.

"[Bashir's] brilliant," Root said. "He's a great young lad to have in the group. I've not seen much of him, and I might not have known much about him before this series, but he's got a great character. He's got a great sense of humour. He takes it all out to the field. And he's clearly, as you can see, got huge amounts of ability and skill and a lot to offer, especially on a surface like this.

"It was great to see him keep coming, time and time again today, asking really difficult questions of their order. And again, he should take a lot of confidence for the rest of this game and moving on as well."

As for the match situation, Root reiterated his confidence that England can close out their advantage, and square the series at 2-2 going into the fifth Test in Dharamsala. In particular, he backed his team to make the most of whatever lead they can secure, and bat with sufficient freedom in tough conditions to post India a challenging target.

On that pitch, 350 looks like a very good score," he said. "I think we're in a good position. Obviously it'd be good to wrap things up quickly tomorrow, but yeah, as a batter you always say, 'it's a terrible wicket, I must have played really well'. But no, I think it's just that odd ball.

"It's just being able to park it mentally, being able to, if it does really misbehave, not let it affect the way you approach the rest of the over, the next ball, and not have any demons about what's gone before. You've just got to react and play and trust your game, and just be really clear about how you want to break things down and score your runs.

"It'd be great to get a sizable first-innings lead on there and then to really drive that home. We've got to be ruthless. We've got to be proactive about how we go and do it, and clear how we want to go and score our runs. But if we can get anything north of 250, it's going to be a very interesting last couple of days."