In a weird way it all began with a pre-season friendly. The sort of game that tends to wipe itself from the memory as soon as it’s finished, sometimes even earlier. A sweltering July night in the Tokyo outskirts. Yokohama F Marinos v Manchester City at the Nissan Stadium for an entirely made-up trophy called the EuroJapan Cup. But in retrospect, it is the moment when a convivial Australian coach called Ange Postecoglou begins his journey to the Premier League.

It’s 2019 and Postecoglou is halfway through his second season in Japan. His first, charitably put, was a mixed bag. There was a cup final but also one of the worst league finishes in the club’s history. There has been relentless attacking football and remorseless defensive collapses. A first relegation from the J-League has been narrowly avoided. But the top brass at Yokohama like the direction of travel. Now, against their parent club and the mothership of the City Football Group, we are about to discover why.

Related: Postecoglou’s Spurs plans go beyond finding way to beat Manchester City

Over 90 breathless minutes, all the hallmarks of a Postecoglou team are present and correct. Furious high pressing. The back four camped on the halfway line. A dribbling, playmaking goalkeeper. Moves built out from the back. Lightning one-touch attacks with runners pelting in from all angles. City win 3-1, largely on the counterattack, but had Yokohama taken one of their many chances the score could have been much closer.

Yokohama finish the game with 58% of possession. To put that into perspective, in Pep Guardiola’s competitive reign at City, only four opposition teams have had more: Arsenal last season, Brighton at the end of 2020-21, Wolves in a freakish Boxing Day encounter in 2019 and Barcelona in Guardiola’s first season. Four times in almost seven and a half years. This is a full-strength City, an almost identical XI to the one that will start the Community Shield against Liverpool the following week, with a full block of training and a full Asian tour under their belts.

“So demanding,” wheezed Guardiola. “An incredible dynamic.” Raheem Sterling went further, praising Yokohama as “probably one of the best teams I’ve seen playing out from the back”.

At full time Postecoglou embraced Guardiola, placing a meaty hand on his bald head as if trying to harness the source of his power. City flew home and turned their attention to more pressing matters. But on the opposite side of the world, a seed had been planted.

For Yokohama, their performance against one of the world’s greatest teams was a resounding vindication of Postecoglou’s methods. “They walked away knowing – and of course it was a friendly – but understanding that even the very best can be tested if you believe in something,” he later attested. “We could play our football.” Having been mid-table in spring, his team surged to the title on a late run of 31 points from 33.

Back in Europe, City were paying more attention than most to Postecoglou’s success. They noted the similarities between Guardiola’s philosophy and the style of football Postecoglou had implemented at their subsidiary club. In the summer of 2021, when Celtic were casting a full-time replacement for Neil Lennon, they were happy to offer their input.

Celtic and CFG have long enjoyed close links, having done plenty of transfer business over the past decade. Mark Lawwell, the son of the former Celtic chief executive Peter Lawwell, was previously a scouting and development manager at CFG. Guardiola knew Celtic’s majority shareholder, Dermot Desmond, well from the celebrity golf circuit, and the Daily Record reported that when they met to discuss the open vacancy, Guardiola heartily recommended Postecoglou, who signed a 12-month rolling contract soon afterwards.

On Sunday, Guardiola and Postecoglou face each other in the dugout for the first time since that night in Yokohama. Guardiola has been lavish in his praise of Postecoglou since his arrival at Tottenham – “Another exceptional manager is coming,” he said on his appointment – and on Friday went even further, claiming that with his aggression and passion, Postecoglou is one of those coaches that “makes football a better place”.

For his part, Postecoglou has tried to play down the links between them. “Check my phone, mate, he’s not in it,” he said in July. But tactically the influence is clear enough, and for all the attention devoted to his homespun manner and natural charm, less is said about perhaps the key driving force behind Postecoglou: his ruthless personal ambition, the desire to keep progressing and keep challenging himself.

Postecoglou builds his teams with the fierceness of a family, but he is not afraid of abruptly breaking them up. He has not spent more than three years at any club since the 1990s. He walked out on the Australia national team just before the 2018 World Cup because he felt the aims of the national federation did not align with his own. Above all, he understands better than most the value of branding: having a clearly defined idea that is innately associated with you and which you can communicate to the outside world.

Related: Premier League’s greed may consume it as Manchester City’s date with destiny looms | Barney Ronay

It is both genuine and an act, in the sense that a large part of coaching itself is essentially an act, the process of selling a vision to players and supporters. It is no coincidence that Postecoglou has made himself extremely visible in the media since arriving in England, always giving interviews, always explaining, always proselytising. There is no vacancy at City for the foreseeable future and Sunday’s game is in no sense an audition. But Postecoglou would not be the coach he is without a strong instinct to prove himself on the very biggest stage.

Opportunism gets a bad press these days, but how else does a suburban Melbourne coach land at one of the world’s biggest clubs if not through an ability to identify opportunities when they arise?

Tottenham go into the game on a run of three straight defeats and in the grip of a defensive injury crisis. The percentage play would probably be to drop 10 yards, squeeze City for space and try to keep the game tight for as long as possible. But Postecoglou knows, as we all do, that percentages are not what got him here in the first place.