If anyone says they know how this Border-Gavaskar series is going to end, they are lying. After it all started with a 17-wicket day in Perth, the second day at the SCG brought 15, which means there might be just one more to go.
When Australia were 39 for 4 it looked like they could be in for a repeat of the first innings at Optus Stadium; as Steven Smith approached 10,000 runs you could imagine them getting a foothold; when Beau Webster and Alex Carey started to forge a stand, with Jasprit Bumrah off the field, a small but crucial lead was on the horizon; when India went through the lower order it was all square.
As Scott Boland did his thing again, including claiming Virat Kohli for a fifth (and likely final) time in Tests, you wondered if he would blow India away; while Rishabh Pant unleashed an extraordinary display the lead was growing rapidly, but Pat Cummins got him for the fourth time in the series; in the dying moments of the day, Smith dived in front of Usman Khawaja and spilled a chance to give Ravindra Jadeja a life.
It was that sort of day. At the end of it, India stood with a lead of 145, with four wickets in hand. The fate of the game, and the series, could well lie in the fitness of Bumrah, whose exit from the ground early in the afternoon, escorted by an ambulance for scans on a back spasm, became as crucial a moment as any.
The reason for such a helter-skelter day, and guessing game as to what happens next, has been the pitch - unlike any seen at the SCG for many years. It's the first time they have used a new variety of grass, called Tahoma 31, for a Test strip here, having experimented with it on Sheffield Shield surfaces last year. On one such pitch, Tasmania were bowled out for 68 chasing 143 as cracks widened and batting became impossible.
It's not quite impossible on this surface, but it's very difficult and one where luck plays as much of a part as technique and skill. Brilliant to watch, but probably not to experience if you are a batter.
"The groundstaff have done an incredible job in terms of creating a wicket with something in it," Australia coach Andrew McDonald said. "Traditionally here it's quite benign and we've had a lot of draws, a lot of people have been talking about the draws, so you are damned if you do, damned if you don't. This game's sped up.
"He's trying to produce an even contest between bat and ball. Has it favoured bowlers a little bit more than what we expected, and the groundstaff expected? There's no doubt about that. It's made for interesting cricket... low-scoring games like this just heighten the pressure in it."
There were a host of different ways batters attempted to find a way. When play began, all eyes were on the resumption of Bumrah vs Sam Konstas. It did not take long for the 19-year-old to lay down his marker, using his feet to smoke a straight drive. From the start of the day, India had a deep third in reaction to Konstas' reverse-scoops at the MCG. But for the beginning of Bumrah's fourth over of the morning they brought him up to third slip. Konstas immediately scooped to deep third. The fielder went straight back. Konstas again wanted to play the role of disruptor.
Ultimately it wasn't Bumrah who got him but Mohammed Siraj, when Konstas edged a booming drive to gully. "There's aggression and aggression, but then there's also playing your percentages," Justin Langer said on Channel 7. "Here, with the ball swinging away, that's a very dangerous shot, to be driving the outswinging ball."
Even Smith, coming off back-to-back hundreds, was hostage to the conditions. Prasidh Krishna's first delivery jumped off a length and climbed towards his chest. When he took Prasidh for six and four off consecutive deliveries, followed by back-to-back boundaries off Nitish Kumar Reddy, it looked like his class would shine through. The summit of 10,000 runs was a mere five runs away when he edged Prasidh to slip.
By this point, Webster had settled into a mightily impressive maiden Test innings having been greeted by an innings threatening to unravel. He was proactive rather than reckless. It was how straight he played that stood out, and he used his big stride to good effect. After his solid role with the ball - he later claimed Shubman Gill as a maiden Test wicket - and safe catching it had become a very handy start to a career. Like Boland's rise to the Test side, it's also reward for perseverance at domestic level.
"I'm defending the stumps and trying to score where I can," Webster told Fox Cricket. "And luckily, I've got a few away today. It was pretty dicey there for a bit, but I felt like once I was into my innings and the nerves settled, it was business as usual."
Webster's was the first half-century of the Test; the second could hardly have been a greater contrast. Pant went from his first innings 40 off 98 balls to a thrill-a-minute 61 off 33 which started with a first-ball straight six off Boland when India had been 78 for 4. Twice in consecutive deliveries he swung Mitchell Starc over the leg side before top-edging against Cummins. "He can turn the game just like that. So we were happy to see the back of him," Webster said.
"We were a little bit surprised in the first innings the way he went about his work," McDonald added. "He's got an incredible ability to put pressure back onto bowlers. We are planned for that, though. We bounced in and out of a few plans there and [he] clearly kept taking on the boundary riders, was getting away with it, and it was an innings you'd say was right for that time."
The right innings, at the right time. The decisive one in this Test match may not yet have been played.