Very few people looking forward to a cricket series can resist speculating and making predictions. Very few ever get it right.

It's a futile endeavour with so many variables at play in a universe that can always surprise us.

Nobody would have predicted India being bowled out for 36, or Steve Smith being unable to make 36 in aggregate until the third Test innings.

Nobody would have predicted a seaming MCG wicket with a match over in four days, or a Sydney pitch without a single crack in it after five.

No one knew which state borders would open and close, and where matches would be played and whether anyone could attend, or that occupants of a Sydney cemetery would be specifically prohibited.

Not many would have guessed that Nathan Lyon would bowl well but struggle for wickets, taking six in three Tests, and that he would enter the fourth and final match in Brisbane with 396 to his name, a chance to reach 400 in his 100th Test.

We could have speculated the series would be close, poised 1-1 heading into the deciding Test. We couldn't have guessed at the path to reach this point, with Australia going through five opening batsmen and India through an entire secondary squad.

It must be a weary arrival at the Gabba. When several Indian players reported racist abuse from spectators across several days of the Sydney Test, they were clearly shaken at the time and fed up later. For the home players, it must make their hearts sink.

"We don't condone the abuse of anyone, let alone from a racial standpoint," said Paine on the eve of the final Test.

"We want everyone to come along to the cricket, support Australia, support India, support the umpires if you like. But leave the abuse at the gate and respect the players and respect the game."

Australia's team must feel emotionally battered. Paine was rightly criticised for his snappy verbals at Ravichandran Ashwin late in the draw at Sydney. Smith was bizarrely accused of cheating after marking guard while fielding.

(For clarity, the accusation of removing guard marks is nonsense given those marks were scored deep into the pitch and are clearly visible on the video before and after the event. There was no accusation from the batsmen at the crease, only backseat drivers on the internet.)

The whole team will be feeling the tension of having lost in Melbourne and having failed to finish off a win in Sydney. Then there was the anxiety of debuting Will Pucovski, the high of seeing him succeed, the low of seeing him injure his shoulder and be out of the team again.

Tourists hit with casualty list

India's team is physically battered. Two years ago while visiting Australia it was a five-strong squad of fast bowlers that underwrote a series win. Ishant Sharma, Mohammed Shami and Jasprit Bumrah played every game, with Umesh Yadav and Bhuvneshwar Kumar as bench strength.

This time India must finish the series with all five of them injured. As are all-rounders Hardik Pandya and Ravindra Jadeja, and batsmen Hanuma Vihari and KL Rahul, while captain Virat Kohli is absent on family business. Opener Mayank Agarwal is in some doubt after being hit in the nets, as is Ashwin with back problems.

That would make a very good international XII on the sidelines.

In Brisbane, Mohammed Siraj will be the attack leader having debuted two matches ago in Melbourne. Navdeep Saini will be his lieutenant having debuted last week in Sydney. Thangarasu Natarajan will likely make his debut. An entire attack with three Tests between them.

Wrist spinner Kuldeep could replace Ashwin if need be, while Prithvi Shaw could open and wicketkeeper Rishabh Pant could play as a specialist bat at six ahead of keeper Wriddhiman Saha. Any more injuries though and coach Ravi Shastri might be making a comeback.

However things work out, the lifting must largely be done by senior batsmen Rohit Sharma, Cheteshwar Pujara, and interim captain Ajinkya Rahane. Their team has fought hard so far and that must be kept going.

If India can cobble together a win or a draw, it will be one of the great touring triumphs. Either will mean the visitors will retain the Border-Gavaskar Trophy. It would also be key to India's hopes of making the World Test Championship final in England in the middle of this year.

Australia is the side that must deal with expectation. All the talk has been of home advantage, of fortresses, of depleted opponents. But there would be an anxiety in the back of the mind about dropping this series after having destroyed the opposition in the first Test.

Paine has to get his head back in the game. Smith needs to keep on with his Sydney runs. David Warner had no influence in his first match back from injury and needs to find something. Matthew Wade might need a score to keep a spot in the team, Marnus Labuschagne needs to find a way to express his enthusiasm without being obnoxious.

The bowlers will have to dig deep after a power of work and a chaser of disappointment in Sydney, especially Lyon with his milestone in view.

"If I'd caught a couple, it could have been very different for him," said Paine of his series.

"Nathan Lyon's played 100 Test matches, that means you're absolutely at the top of the tree. At times the Indians have played him very well, but at times we know looking at the footage he's created plenty of chances. He'll have a huge role to play in this Test for us."

One more match then, to decide yet another absorbing series between two teams who have hardly played a bad one in the last 20 years. Predicting the result is pointless. It's time to enjoy finding out.