It was lunch on day three and Tamil Nadu were trailing Mumbai's first-innings total by 29 runs with only two wickets in hand. While most members of the Tamil Nadu camp might have been plodding through an anxious meal, a group of players and support-staff members headed to a distant corner of the Bandra-Kurla Complex ground for a net.

R Ashwin was at the front and centre of the group. His India commitments mean you don't often see him in a Tamil Nadu jersey - since his international debut in 2010, Ashwin has turned out for his state only 19 times across formats. Before this season, his most recent Ranji Trophy appearance had come in a rain-affected game in 2012. So, for the likes of B Aparajith and Ganga Sridhar Raju, who were going to be Ashwin's sparring partners in the nets, this was an opportunity to watch their senior partner from close quarters and learn from him.

Ashwin, on the other hand, could have used whatever game-time came his way in his build-up to the three-Test series at home against Sri Lanka followed by a demanding trip to South Africa. There are other factors, too, that would doubtless have been spurring him on. He hasn't figured in India's limited-overs plans recently after being "rotated out" for the series against Sri Lanka, Australia and New Zealand. His absence has since coincided with the rise of two young wristspinners - Yuzvendra Chahal and Kuldeep Yadav - who, according to captain Virat Kohli, have been so good that he has been tempted to play them in every game.

Ashwin himself wasn't going to leave the wrist-spin base uncovered. As he has been doing often, lately, Ashwin invested time and effort in bowling legbreaks. To the left-hand batsman Raju, he even bowled the flipper, often on the shorter side of a good length. When he bowled to Aparajith, a right-hand bat, he went over the wicket and from a run-up of eight or nine steps, tried different lengths and lines. He constantly checked with the batsmen and L Balaji, Tamil Nadu's bowling coach, if the ball was getting enough drop or if there were too many "freebies."

On Thursday, Ashwin would get a crack at putting his plans into work in the middle. They would be subjected to a severe examination, though, by one Mumbai batsman. Over the afternoon and on the following day, he would second-guess and eventually dismantle Ashwin's plans. The batsman was Shreyas Iyer.

Hard numbers, stripped of nuance, would tell you that Iyer won the duel with Ashwin, by pinfall and submission. He scored 37 off the 40 balls he faced from Ashwin, including three sixes and two fours; on Friday alone, he made 22 off 21. But, the broader story lies in the subtext and the circumstances.

At 22, Iyer is currently hot property. For long recognised as one of the country's best young batsmen, Iyer has backed up the hype with some barnstorming performances in the last few months. It got to a point where the selectors could no longer confine him to to A-team cricket, and included him for the T20Is against New Zealand next month. Right from his higher-than-usual backlift against fast bowlers on Friday to his nonchalant shrugs, everything about him screams swag.

At the other end of the spectrum is Ashwin, nine years Iyer's senior and with an experience of 209 international games. As India's main spinner for a few years now, he's almost expected to turn up and knock batsmen over, particularly if it's a domestic fixture. Ashwin had tried bowling around the stumps to Iyer on the third afternoon, but the ploy backfired after Iyer smacked him for two sixes, one of which went out of the park.

It wasn't until after 12 overs on the final day that Ashwin was given the ball for the sequel of their stoush. Iyer was then on 84 and was racing towards a hundred. There was little of the abrading that is said to be the mark of a fourth-day subcontinental surface; except for the odd ball, there was very little turn on offer. So Ashwin continued to operate from around the stumps with a 3-6 field, and initially kept Iyer quiet. He did it by landing the ball on middle and leg and turned the ball into the body, and on occasions, outside leg. Every now and then, he would use the carrom ball and also slant one across the stumps.

It seemed like a sound strategy at first, as it denied Iyer the hitting width he craved for. Up to that point, Iyer had been brutal on anything remotely outside off stump, either carting it over the bowler's head or drilling it through the covers. When you combine these factors, it is fair to expect Iyer to lose his rhythm at some point and attempt something rash. Except, that didn't happen. Iyer knew the field was spread out for him - the Tamil Nadu captain, Abhinav Mukund, later reasoned that Iyer was anyway going for lofted shots, so there was always the possibility of a mistimed hit that would result in a catch - and knocked Ashwin around for singles and twos. Whenever he couldn't lay bat on ball down the leg side, he was happy to leave. One of those deliveries was even called wide.

On only one occasion did Ashwin come close to getting Iyer out. He slid one across the batsman, who slashed hard and edged, the ball flying quickly to the left of slip for four. Soon after, Iyer completed his hundred, and in a repeat of his shot from Thursday, whacked Ashwin over the wide long-on fence. Ashwin appeared a little rattled, and bowled a faster, shorter legbreak the next ball. This time Iyer went back, held his shape, and steered it behind point for another four. He would invariably follow such shots with a single to sweeper cover or deep square leg.

Ashwin went back to bowling over the stumps - a touch belatedly, perhaps - but Iyer had messed his plans up by then. Ashwin's uninterrupted 11-over spell had cost him 50 runs. An extension of the contest, however, was not to be seen as Iyer was run out before lunch. Perhaps that was the only way Tamil Nadu could have got him out.

Arun Venugopal is a correspondent at ESPNcricinfo. @scarletrun