In a year of unprecedented upheaval in Australian cricket that has left the Test batting line-up in a seemingly constant state of flux, it will be of some comfort to national selectors that – fitness pending - their focus has rarely had to stray beyond No.7 in the batting order.

Two days out from their first Boxing Day Test as a foursome, Australia’s world-leading bowling attack remains the major obstacle standing between India and a first-ever Test series win Down Under.

The Australians have restricted the world’s No.1 ranked Test side to four scores of 307 or less in the past four weeks, including a fourth-innings demolition in Perth to seal a first Test win in more than 10 months.

And in an ominous sign for the tourists, coach Justin Langer believes “they haven’t quite nailed it yet”.

Nathan Lyon, Pat Cummins, Josh Hazlewood and Mitchell Starc enter the Third Domain Test as the world’s sixth, seventh, eighth and 15th ranked Test bowlers respectively.

As close as they are in the rankings, Starc says it’s their tightness off the field that makes them such an unstoppable force on it.

“All attacks are very different, but one thing unique about this group is we’ve all grown up together,” Starc says.

“We’ve played a lot of cricket together … we’ve grown up through the ranks together (and) spent so much time with each other off the field.

“We’re best mates off the field as well and I think that comes to life in our cricket (with) how much we enjoy playing alongside each other.

“I think the whole group really complements each other really well. We do different things and when you’ve got Nathan Lyon doing the job he does, it makes the job of the quicks so much easier.

“We’ve got a left-armer, two right-armers who do completely different things … and Nathan speaks for himself. It’s just a great group to be part of.”

Hazlewood adds: “We’ve played a lot of cricket together now and we all know each other very well off the field as well as on the field.

“It’s just about knowing how each other’s going about it and when we might need to have a word, or (not because) they know what they’re doing.

“It’s that experience of playing together, those sorts of relationships form, and you just become a lot closer.

“Bowling is very much a combined effort from everyone rather than just one good spell here and there. It’s about maintaining pressure for 90 overs a day and if the four of us are on, we know we can do that for days on end.”

But there is a small divide in this team within a team.

The quicks have the exclusivity of the famed Fast Bowling Cartel, the trio even meeting up for gym sessions in Sydney this week as the Australians celebrated their breakthrough victory in Perth with a few rare and well-earned days in their home ports.

Yet even these three proud fast bowlers concede it’s the spinner, Lyon, who holds the group together.

“He plays that role where he can hold up one end and not go for runs, or generally take a wicket, and sometimes do both,” Starc says.

“In a group of four bowlers, when the spinner’s doing that, it just allows the quicks to come from the other end a bit fresher and bowl fast and aggressive and attack from both ends when Nathan’s on the way he is.

“It just rounds out the group so well.

“He continues to shape his game and he’s been unbelievable over the past 12-18 months. He keeps adapting week by week, which is outstanding for someone who’s taken over 300 wickets like he has.”

Having played the bulk of his career alongside bowling icons like Shane Warne and Glenn McGrath, Langer knows just how valuable a commodity he has at his disposal.

But in these uncertain times, he also knows how much he needs them to fire on all cylinders.

“All of them would admit that they haven’t quite nailed it yet in this series, so that’s exciting,” Langer said on Monday.

“We saw it in the Ashes last year, there were times they were all over England because they functioned so well as a group.

“I’m really excited, whether it’s in this Test match or in Sydney, when those guys bowl as that unit … I can’t wait to see that.”

And if Langer gets his Christmas wish, India’s 70-year winless streak on Australian soil will continue well beyond this summer.