National men's coach Justin Langer says Marnus Labuschagne could shuffle down the order from his incumbent first-drop position for the first Test of the summer as selectors ponder the make-up of Australia's batting order.

Labuschagne has batted five times at No.3 in Test cricket this year, making scores of 38, 67, 11, 48 and 14, and was a revelation in England when called in to the side to replace a concussed Steve Smith, posting four straight half-centuries.

Three of those came from the No.4 slot, however, the same position from which he has posted 225 runs at 75 for Queensland in the Marsh Sheffield Shield so far this summer.

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With Smith occupying the No.4 spot in the Test team, Labuschagne's position is set to hinge on which other batsmen are picked for the first Domain Test against Pakistan in Brisbane, beginning November 21.

"Time will tell (where he bats), but he'll certainly be in the first Test team," Langer said. "He's done a really good job. He's played well in England, he's played well back here.

"Where he bats will be dependent on who the other selections are."

The selection of a strong Australia A squad on Tuesday offered indications as to the selectors' focus in terms of who is vying to fill the remaining two batting slots in the top six; alongside Labuschagne and Smith, opener David Warner is tipped to retain his place despite a lean Ashes campaign, while the two hundreds scored in England by Matthew Wade are thought to have shored up the Tasmanian's middle-order spot for the series opener.

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If two of the Australia A trio of Joe Burns, Usman Khawaja and Marcus Harris find themselves back in the Test team in the top three, Labuschagne could slot into the side at No.5, with Wade returning to six despite his century in the final Ashes Test at The Oval coming from third drop.

However, if only one of the aforementioned three re-earn Test selection, Labuschagne could well stay at No.3, with perhaps Travis Head slotting in behind Smith.

Australian teammates Travis Head and Marnus Labuschagne cross paths during the Marsh Sheffield Shield // Getty

Complicating the matter further still is brilliant young Victorian Will Pucovski, whose three most recent first-class hundreds have come from No.3. Against what looks set to be an inexperienced Pakistan pace attack, selectors might be willing to introduce Pucovski to Test cricket at first drop.

Langer said a scenario where Khawaja opened the batting and Burns came in down as low as six was also "realistic" and stressed that top-order batters in the Sheffield Shield give themselves more chance of Test selection than those in the middle-order.

"I've always said if you can bat top three in Shield cricket, you can bat anywhere in the order,” he said. “Whereas if you bat down the order, you're probably just specialising in one position and you give yourself less opportunities.

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"We're looking to cement a (Test) top three – so there's some good opportunities there.

"(Runs for Australia A) will help, and I think we've shown not just with this selection but leading up to the Ashes as well, we had guys playing Australia A and also county cricket.

“We're really fortunate to have guys playing for Australia A in that three-day game against Pakistan, and some guys playing Sheffield Shield cricket.

"So we'll keep pushing the point – keep performing, keep knocking on the door and there's certainly one or two spots up for grabs for the first Test."

Domain Test Series v Pakistan

Australia squad: TBC

Pakistan squad: Azhar Ali (c), Abid Ali, Asad Shafiq, Babar Azam, Haris Sohail, Imam-ul-Haq, Imran Khan Snr, Iftikhar Ahmed, Kashif Bhatti, Mohammad Abbas, Mohammad Rizwan (wk), Musa Khan, Naseem Shah, Shaheen Shah Afridi, Shan Masood, Yasir Shah.

Warm-up match: v Cricket Australia XI, November 11-13, Perth Stadium (d/n)

Warm-up match: v Cricket Australia XI, November 15-16, WACA Ground

First Test: November 21-25, Gabba (Seven, Fox & Kayo)

Second Test: November 29 – December 3, Adelaide (d/n) (Seven, Fox & Kayo)