Cheteshwar Pujara is not prone to lapses in concentration. He doesn't leave the oven on after he's finished cooking, he doesn't leave the back door unlocked, and he certainly doesn't get out to left-arm orthodox spinners.

At 9.50am on Tuesday, it had been nearly four years since a left-arm fingerspinner had dismissed him in a Test match. In that time, he had soaked up more than 140 overs against them, scoring 375 runs in the process. And then Jack Leach found some drift into him, some turn and bounce away from him, and drew an outside edge which flew to Ben Stokes at slip.

If James Anderson's epic over to Shubman Gill and Ajinkya Rahane set the wheels of England's final-day win in motion then Leach's dismissal of Pujara had revved the engine, put it in gear and found the biting point. Last month, Pujara had soaked up 416 balls across the fourth innings of India's draw in Sydney and their dramatic win in Brisbane, wearing multiple blows from the seamers and negotiating more than 20 overs of Nathan Lyon's offspin in a pair of epic rearguards; in Chennai, he lasted less than 25 minutes on the final morning.

Pujara's wicket - and that of Rohit Sharma on the fourth evening - provided Leach with his hard-earned rewards after a chastening experience on the third afternoon that would not only have thrown many bowlers off for the rest of the Test, but left scars that affected their confidence for weeks and months to come.

Leach had been given a specific role by England in that session: to toss the ball up into the footmarks outside Rishabh Pant's off stump, and keep doing so regardless of how he responded. Pant blazed five sixes in 21 balls, taking Leach for 48 runs and leaving him with figures of 8-0-77-0 - eye-wateringly expensive in a 50-over game, let alone a Test match in helpful spinning conditions.

But Jeetan Patel, England's spin-bowling consultant, insisted that Leach's pitchmaps from the third day showed how well he had stuck to his task. "We're always going to look at outcomes, aren't we?" he asked rhetorically. "Statistically, he was really good, and the balls that he bowled were in the right areas. Rishabh Pant is a very good player who struck the ball nicely, and he got away with a couple. [Leach] had done a lot of good things, but it just hadn't gone his way."

"I thought I was playing in the IPL," Leach joked after the fifth day. "It was a challenge, definitely. As a spinner, you've got to expect that at times, but I'm never going to enjoy eight overs for 80 [77]. It's just about trying to stay strong and the boys really helped me out. It was a tough evening that evening, but I just wanted to come back strong on the last two days."

And so he did. Crucially, having lost sight of his plan to Pujara while Pant was taking him down, Leach regained his control and composure, landing the ball on a length outside the off stump and letting natural variation from the pitch do the rest of the work. His last 16 overs in India's first innings cost 28 runs, including the wickets of R Ashwin and Shahbaz Nadeem on the fourth morning.

It was his performance in the Test's final innings that proved crucial. While his partner Dom Bess seemed to lose his rhythm and consistency as the game wore on, Leach's picked up as it so often does. Bowling in the third and fourth innings, Leach has taken 36 Test wickets at 20.08; no other spinner's record since his debut can match his when the pressure is on to bowl sides out.

In particular, he was superb when landing the ball on a good length. According to ESPNcricinfo's ball-by-ball data, 78 of the 156 balls Leach bowled - exactly half - pitched on a length, from which he took three of his four wickets and conceded only 10 runs off the bat. He may be something of a throwback - Leach has never played a professional T20 game - but he does the basics of red-ball spin bowling extremely well. He returned after lunch to dismiss Ashwin and Nadeem, the latter his 50th Test scalp in just his 13th appearance.

It should be noted that Leach benefited in the first Test from bowling to a line-up featuring nine right-handed batsmen, and an exclusively right-handed top five. Against right-handers, Leach has taken 40 Test wickets at 24.45 while conceding 2.63 runs per over, numbers which outstrip every spinner's other than Ravindra Jadeja (39 wickets at 21.48) since his debut. Against lefties, he has leaked 4.01 runs per over, and taken 10 wickets at 54.50.

But he has shown signs of adaptability that suggest he will improve on that record, and he has made use of his experiences in domestic cricket throughout his fledgling international career. On the fourth evening, for example, he was tasked with opening the bowling, as he had done twice on England's tour of Sri Lanka in 2018 and seven times for Somerset on turning pitches in the County Championship. He responded with the early wicket of Rohit, kissing his off stump with the best ball he has bowled in an England shirt.

"There are moments when I feel like I can use what I've done in the past on those kinds of wickets to maybe realise times that I want to stick in and bowl consistently and not go for too many, and then other times when I'm prepared to take a few more risks, change my pace or whatever it is," Leach said. "I'm just glad we got the win: it was a real team effort so I'm very happy."

Leach has become something of a cult figure among England fans, and it is easy to see why: he looks slender and unassuming, he wiped his glasses throughout his famous 1 not out in the Ashes win at Headingley, made 92 as a nightwatchman against Ireland earlier that summer, and has an inspiring story of off-field resilience including re-modelling his bowling action and living with Crohn's disease.

But perhaps the focus on Leach the man has distracted from the abilities of Leach the bowler. He's the only member of their attack to have featured in each of England's record run of six consecutive wins in Asia, and with 34 wickets at 27.08, he's been fundamental to their fortunes too. If he can help turn England's 1-0 lead into a series win in India, he will go a long way towards redressing that balance.

Matt Roller is an assistant editor at ESPNcricinfo. He tweets at @mroller98