From a neutral's perspective, the India-England series couldn't be better set up going into the third Test. It's 1-1, and neither team can be entirely sure of what to expect in Ahmedabad. The Sardar Patel Stadium hasn't hosted an international game since 2014, and is now entirely refurbished, with a world-leading 110,000 seating capacity. And this, of course, will be only the second time India hosts a day-night Test, which will bring an entirely new set of variables into play because of the floodlights and the pink ball. Here's a guide to what Motera might have in store for us.
The ball
The major point of difference between the SG pink ball and its red counterpart is in how colour is applied to its leather exterior. While the leather of the red ball goes through a dyeing process, the pink ball is coated with multiple layers of pigment. And to enable these coatings to last longer, the pink ball is finished off with an extra layer of lacquer.
When Kolkata hosted India's first pink-ball Test in 2019, this extra lacquer led players to feel the ball was coming onto them quicker than expected - in the air and off the pitch - and that it felt harder and heavier when it hit the fielders' hands. The longer-lasting shine also helped the ball swing - often prodigiously - for longer.
But the shine lasted as long as it did because the curator at Eden Gardens left 6mm of live grass on the pitch. It wasn't a difficult decision then, because India possessed a seam attack that was decidedly superior to Bangladesh's. India's opponents this time are England, which complicates the issue a little.
The pitch
Traditionally - if we can use that word for a concept that's only in its sixth year - day-night Tests have tended to favour the faster bowlers. In the 15 day-night Tests that have been played around the world, fast bowlers have taken 354 wickets at an average of 24.47, and spinners 115 wickets at a significantly worse 35.38.
In the Eden Gardens pink-ball Test, every wicket India's bowlers took went to their fast bowlers, and their spinners, R Ashwin and Ravindra Jadeja, only sent down seven overs between them across Bangladesh's two innings.
But the trend for day-night Tests to disproportionately favour seam and swing is mostly down to curators leaving extra grass on the pitch to ensure the pink ball stays harder and retains its shine for longer.
Five days before the Test match, the Motera pitch was indistinguishable from the outfield. There was far less grass on the surface a day later, though, and it's anyone's guess as to how much remains by the time the Test match begins. With England boasting one of the best and most varied pace attacks in the world, there probably won't be any more than the bare minimum necessary to maintain the pink ball's integrity.
#Pitchwatch with @englandcricket captain #JoeRoot casting his eyes over the surface for the third #INDvENG Test in #Ahmedabad... pic.twitter.com/FH3Hetxhji
— Brian Murgatroyd (@murgersb) February 20, 2021
If there's little or no grass on the pitch, we may have to brace for a pink ball that gets discoloured. Ahead of the Test match, this was the biggest concern that Paras Anand, the marketing director at SG, expressed in a chat with ESPNcricinfo. He was confident the ball would be no different to the red ball in terms of how well it retained its shape or its seam, but he felt that a pitch with little or no grass would "definitely take a toll on the colour of the ball".
Visibility
One of the most spoken-about topics during the Kolkata pink-ball Test was the visibility of the ball under lights. As many as four Bangladesh players were hit on the head by bouncers, and they ended up using two concussion substitutes over the course of the match.
Feedback about visibility was mixed, with some representatives from both teams suggesting it wasn't an issue, and others - most notably Cheteshwar Pujara - saying it was a bit of a challenge under lights.
The new Motera stadium doesn't have traditional floodlight towers, but a ring of LED lights around the perimeter of its roof. It's similar to the "ring of fire" at the Dubai International Stadium, and this could potentially impact visibility too. During IPL 2020 in the UAE, a significantly greater percentage of catches were put down in Dubai than at the other two venues, but high catches are far less frequent in Test cricket than in T20.
Will dew play a role?
Speaking ahead of the Motera Test, Pujara reckoned that dew might set in during the final sessions of the Test match. This could have a number of consequences.
During the Eden Gardens day-night Test, the pink ball was changed once, in the 59th over of India's only innings, when it went out of shape. This, according to Anand, was because of the older ball soaking up dew. He's confident that the work that's gone into the SG pink ball since then will help it retain its shape even if there's dew.
Even if the ball doesn't go out of shape, it could stop swinging if it gets wet. Equally, it could become harder to grip for the spinners. Batsmen, on the other hand, tend to enjoy themselves when there's dew, with the ball often zipping off the pitch quicker - with less lateral movement - and coming onto the bat better.
This was a key factor behind batsmen dominating the Dubai day-night Test between Pakistan and West Indies in 2016, with a wet ball hindering both turn and reverse swing.
Will there be turn? And what about reverse swing? For all the talk about seam and swing in the lead-up to the game, Ahmedabad may just throw up another turner. This is what Rohit Sharma feels. "It'll turn," he said on Sunday. "We're preparing accordingly for that, let's see when the day comes."
While India's seamers dominated the Kolkata day-night Test, Bangladesh got more work out of their spinner Taijul Islam, who sent down 25 overs. When asked how much turn there was, Pujara compared the pink SG ball to the pink Kookaburra that he had faced in domestic cricket.
"When I played Duleep Trophy with the Kookaburra ball, I don't think there was much assistance for spinners, apart from the wristspinners," he said. "So with this ball I think there is some spin. We saw when Taijul [Islam] was bowling, he got a little spin, and Ashwin also got a little bit of spin. So I think there's a little more assistance for spinners. But it is still not as much as what you get from a red ball."
The line about wristspinners was instructive, because players around the world believe the wrong'un is harder to pick when it's delivered with the pink ball under lights. South Africa picked the left-arm wristspinner Tabraiz Shamsi as a pink-ball specialist for the Adelaide Test in November 2016, and there is a chance India could do the same with Kuldeep Yadav here, though their team composition may make it difficult to accommodate him.
Reverse swing is another variable that may or may not be in play. Generally, the lusher pitches prepared to preserve the pink ball have worked against the possibility of reverse swing, but we might see some if Motera is drier and more abrasive than the typical day-night pitch.