Australia's top order: What are the selectors' options?

There's a one-day series going on against India, but the main topic of conversation in Australian cricket is what the selectors will do with the squad for the first Ashes Test in Perth. Decision day is looming with one more round of Sheffield Shield to be played and while a few things are becoming clearer the big calls are still to be made.

The fitness of Pat Cummins looms large over everything. But on the assumption he misses at least the first Test, which is all-but certain, and Scott Boland slots into the attack, the major talking points around the final XI will remain the top order. Here we run through three potential scenarios that George Bailey, Tony Dodemaide and head coach Andrew McDonald will be pondering. There is also a chance that the squad announcement won't clarify everything, with the final calls not taken until the eve of the first Test.

Option 1: One in, one out

Khawaja, Labuschagne, Green, Smith, Head, Webster, Carey, Starc, Lyon, Boland, Hazlewood

If the only spot vacant is an opener, then Marnus Labuschagne's irresistible claims for a recall will see him go in at the top alongside Usman Khawaja as he did in the World Test Championship final against South Africa at Lord's. That was a last-ditch move from the selectors, basically honouring Labuschagne's role in getting them to the final, and he was dropped the Test after. He will be in much better form heading into the Perth Test should the role come his way again.

"He can open…he can bat three. He's versatile," Steven Smith said. "We'll see where it all stands when the team gets picked. I mean, it's not too different to batting three, to be honest. He could be in first ball. So, it's essentially the same thing."

This team also means Beau Webster's bowling is retained which would take the pressure of Cameron Green to send down too many overs as he continues to work his way back with the ball even if his withdrawal from the India ODIs was described as a conservative decision. It keeps Green at No. 3 where he finished the West Indies series with scores of 52, 46 and 42 in tough batting conditions.

Webster has missed the first two rounds of the Sheffield Shield after rolling his ankle but will feature against Victoria in Melbourne and last week Bailey confirmed he would be part of the Test squad.

Option 2: Marnus at No. 3, Webster unlucky

Khawaja, [An opener], Labuschagne, Smith, Head, Green, Carey, Starc, Lyon, Boland, Hazlewood

While it's often said there is very little difference between opening and No. 3, Labuschagne's best position is No. 3. If there was a decision made that he has to return in that slot, then an opener is still needed. That creates a few scenarios.

Sam Konstas has been unconvincing in two Shield rounds, but a big score against Queensland, at a Test venue in the Gabba, would be an interesting twist. Uncapped Jake Weatherald has played arguably the most significant innings so far among the contenders with 94 off 99 balls in a low-scoring contest against Western Australia. Matt Renshaw started the season with a century for Queensland and has since earned an ODI recall. Would runs against India in the next two games be of any significance? And then there's Mitch Marsh…

This balance of top order would see Green move back down to No. 6 and require the selectors to have complete confidence in him being able to operate close to, if not completely, unrestricted as a bowler so that he can ease the burden on the three frontline quicks. If that was the case, Webster would very unfortunately be sidelined.

This XI is the same as option one but with a subtle shift in the order. Smith returns to No. 3 and Green drops one spot to No. 4, where he made 174 against New Zealand early last year before his back injury. It's an outcome endorsed by a number of pundits, including Mark Waugh, who believe that it is Green's natural position.

"I think he can bat anywhere," Smith said of Green. "As he showed in the West Indies, I thought he batted really nicely at three. You know, he's got a really good technique, good temperament. The beauty with our line-up, I think everyone can sort of slot in at different spots and be versatile."

Smith, meanwhile, has averaged 67.07 from 29 innings at No. 3 but, while on Tuesday he said he wasn't "too fussed" about batting orders, he may be reluctant to shift again after the opening experiment.

Whichever batting line-up Australia settle on for Perth, there's a very good chance it's not the one which finishes the series in Sydney. If Khawaja struggles early on it will raise questions about whether Australia need to bite the bullet and find another opener. And what happens if Labuschagne is picked to open and starts poorly in the first two Tests? There are also, probably unfairly given his early success, still a few questions asked about whether Webster's technique will stand-up long term in Test cricket. Josh Inglis is a versatile batter who the selectors value highly and he would come into the mix should anyone struggle or be injured.