After being called into the squad in place of Nathan McSweeney, the 19-year-old was on Tuesday confirmed to be part of the XI at the MCG by Australia coach Andrew McDonald.
At 19 years and 85 days on Thursday, the NSW whiz-kid will be Australia's youngest Test cricketer since his captain, Pat Cummins, debuted at 18 years and 193 days in South Africa in 2011.
Konstas will beat the 95-year record held by Archie Jackson, who opened the batting aged 19 years and 149 days back in 1929.
Australia will be celebrating if Konstas comes even close to what Jackson achieved on debut, smashing 164 against England at Adelaide Oval.
Incoming Australia opener Sam Konstas arrives for a training session at the MCG. (Joel Carrett/AAP PHOTOS)
"We said from the get go, leading into the summer that we wouldn't shy away, and age was no barrier," McDonald said.
"What he's (Konstas) shown is an array of shots, the ability to put pressure back on to opponents.
"He gets his opportunity, so we're really excited for him. Boxing Day, the biggest stage.
"Any time you get a debutant, it's a moment in time, isn't it.
"In particular, how young and how free he's going to play."
The last time Konstas played at the MCG, he made three and 73 not out for Australia A last month against India A.
Konstas blasted 107 from 97 balls against India in Canberra three weeks ago, keeping him in the Test frame even though McSweeney initially started the series as Usman Khawaja's opening partner.
But Travis Head failed to train fully as Australia sweat on the fitness of their most important player just two days out from the the start of the fourth Test.
Travis Head had a short session in the MCG nets on Tuesday. (Joel Carrett/AAP PHOTOS)
McDonald said he was "really confident" Head would play but still needed to overcome a small calf strain.
"There's no concern at the moment," McDonald said.
"Has he been officially ticked off? I'm not sure. I didn't see the sort of back end of his training session there, but I'm pretty confident he'll play.
"It'll just be basically what risk is associated with that.
"He had a small strain to the quad.
"But no concerns from my end, he's been able to do his running, so I think it'd be fully functional come game time."
After not training a day earlier, the star left-hander had a short stint in the MCG nets on Tuesday when he received throw downs for about 20 minutes.
Head had a long conversation with McDonald and team physio Nick Jones before going back into the rooms.
Other batters Steve Smith, Usman Khawaja and Marnus Labuschagne all had extended periods in the nets facing the likes of Mitchell Starc at full pace.
Earlier, Head had a short stint of catching practice, but didn't do any meaningful running.
The 30-year-old has been in rare form, smashing centuries in Adelaide and Brisbane to certify himself as India's most in-demand wicket.
Head has made 409 runs at an average of 81.80 across the first three Tests of the Border-Gavaskar series, dominating India even as the rest of Australia's batters have faced significant issues against Jasprit Bumrah.
If Head doesn't play, Australia's white-ball keeper Josh Inglis would likely come in as a batter-only for his Test debut.
Tasmania allrounder Beau Webster is also pressing his case for selection, but No.6 Mitch Marsh appears to have overcome his back issues after bowling more than he has since the first Test in Perth.
Marsh delivered just two overs in the rained-out Test at the Gabba, but McDonald expects him to play a greater role with the ball in Melbourne.
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