Head brought up his maiden SCG Test ton off 105 balls early on Tuesday, as Australia moved to 2-179 early on day three in reply to England's 384.
While questions remain over Australia's opening pairing after Jake Weatherald's wasted start on Monday, Head's move up from No.5 is now entirely vindicated.
The left-hander brought his century with the 17th boundary of his innings, following his 69-ball ton hundred in Perth and big 170 in Adelaide.
Australia have indicated they will re-evaluate whether Head should remain as opener at the end of this summer, or move back down the order.
But with questions over Weatherald, it's hard to see any option other than Head staying at the top when Australia next play Test cricket, against Bangladesh in August.
With Head reaching his third century of the series on Tuesday, he became the first Australian opener to do so in an Ashes battle since Matthew Hayden in 2002-03.
The 32-year-old, who was only moved to the top of the order in the second innings of the first Test due to Usman Khawaja's back injury, already has the most runs in a series by an Australian opener this century.
"The way (Head) can score off the top of the stumps, both sides of the wicket, he makes your margins very small," England star Joe Root said.
"And he has such incredible hand-eye coordination.
"He's very good at putting bowlers under pressure at the right time and making it very difficult to build a sustained period of pressure over the partnership.
"He is always looking to throw punches back in his own way, and he has got a very clear method of how he wants to do it and trusts it."
Long earmarked as one of the most talented players in the country, Head has now been part of the national set up for a decade this month.
But it has been in the past four years that the South Australian has come into his own, becoming a more fearless batter on his return to Test team in the 2021-22 Ashes.
"Knowing him from his younger days, he was still figuring out his game," said teammate Michael Neser, who spent time with Head at the Adelaide Strikers early on.
"At the moment, he looks real clear in what he is doing. Every ball he is looking to score.
"He is not trying to work it around or grind it out. He is looking to score every opportunity he gets.
"And most times he creates more opportunities than normal batters, because he is so talented. His hand-eye is amazing.
"You think you have beaten him with a ball and then all of a sudden he has slapped it through point for four."
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