Marcus Harris is no sure thing to be dropped from Australia's Ashes team for the fifth and final Test, starting in Hobart on Friday.

A selection spanner was thrown in the works during the Sydney Test. With Travis Head forced out of the side due to a positive COVID test, it allowed Usman Khawaja to come into the middle-order, and the veteran batsman didn't disappoint.

Taking Head's number five role, Khawaja made a century in each innings which almost guided Australia to a victory which would have moved them 4-0 ahead in the series, the bowlers eventually falling one wicket short of completing the job.

Despite Khawaja's work in Sydney, he is no sure thing to keep a spot in the side with Head set to return from isolation.

Khawaja himself has said he expects to be dropped, despite the fact he averages more than 90 as an opener in Test cricket, and the fact Marcus Harris has made just a single half-century this summer.

Despite that, national selector Tony Dodemaide said the innings in Melbourne won Australia the game, and that opening was a different challenge to batting number five, indicating the selectors are yet to make up their collective mind on the make-up of Australia's XI for the fifth Test, to be played under lights.

BRISBANE, AUSTRALIA - NOVEMBER 24: Usman Khawaja of Australia looks dejected after being dismissed by Moeen Ali of England during day two of the First Test Match of the 2017/18 Ashes Series between Australia and England at The Gabba on November 24, 2017 in Brisbane, Australia. (Photo by Ryan Pierse/Getty Images)

"That was just a phenomenal performance from 'Uzzie' (in Sydney)," Dodemaide told reporters on Tuesday.

"Having said that, there is a lot of conversations to be had over the next couple of days. It's a very difficult one. It's a great place to be when there's so much competition for places.

"What we also remember too is only a week-and-a-half ago, Marcus probably played the most consequential innings of the game in Melbourne and set up that (first innings) for Australia which won us the game.

"It's very different batting at the top of the list compared to batting at five and Uzzie said that himself.

"So there's certainly some challenging conversations for us over the next 48 hours or so."

Given the pitch was a difficult beast to bat on in Melbourne, and Hobart could play the same way - particularly following heavy rain, the selection of Khawaja is not a given.

Harris has also played in two pink-ball Sheffield Shield games in Hobart, which could work in his favour.

The Test gets underway on Friday afternoon.