'Relentless' Postecoglou tasked with breaking Tottenham's cycle of failure
There is, however, significant work to be done.
Postecoglu boasts a remarkable record, having won successive A-League titles with Brisbane Roar in 2011 and 2012.
He guided Yokohama F Marinos to their first Japanese top-flight league title in 15 years in 2019 and had a four-year stint with Australia during which he led them to the 2014 World Cup and secured their first major title at the Asian Cup.
He leaves Celtic having bolstered an already impressive CV, with five domestic trophies in two seasons at the Scottish champions.
Now, as he becomes the first Australian to manage a team in the Premier League, he faces one of his greatest challenges yet in turning around a side that have not won anything in 15 years.
MASSIVE TASK
Postecoglou is the eighth permanent manager to be appointed by Spurs since they won the League Cup in 2008, their last piece of silverware.
The 57-year-old will be tasked with reviving the fortunes of the north London club, who finished eighth last season and missed out on European football for the first time since the 2009-10 season.
Since reaching the Champions League final in 2019, Spurs have been in steady decline, finishing sixth, seventh, fourth and then eighth in the following four seasons after a run of four straight top-four finishes from 2015-19.
Off the field things have been no better.
Spurs are without a director of football, with Italian Fabio Paratici having resigned in April after his appeal against a 30-month worldwide ban over his role in transfer deals and finances while at former club Juventus was rejected.
Their England captain Harry Kane (29) who turns 30 next month and has yet to win a trophy at the club he has called home since he was 11, is in the last 12 months of his contract.
In a Sky Sports interview last month, Kane said the club had "lost a bit of what the values are" over the last few years, and he has been linked with a move away from the Premier League side - a situation that is high on Postecoglou's list of priorities.
Yet despite the Australian's overflowing in-tray, his track record at Celtic should give cause for optimism.
CELTIC REBUILD
Postecoglou's success at Celtic was no mean feat. He took over right after they missed out on a record 10th consecutive title and finished 25 points behind bitter rivals Rangers.
The ex-Australia defender has a reputation for being ruthless in clearing out players in under-performing teams before guiding his new charges to success.
He oversaw an overhaul at Celtic Park, bringing in 12 players in his first transfer window while letting eight go, including the likes of Odsonne Edouard (25), Kristoffer Ajer (25), and Ryan Christie (28).
More astute signings were made in the next window, with Matt O'Riley (22) plus Japanese pair Reo Hatate (25) and Daizen Maeda (25) coming in before the Glasgow club finished four points ahead of Rangers to seal the Scottish league title in Postecoglou's first season.
A year later, Celtic's dominance was even greater.
Under Postecoglou, they averaged the most goals per game (3) and the highest average possession (73%) of any team in Europe's top 10 leagues in 2022-23, as they won the league with four games to spare and clinched a domestic treble.
"To win five out of six domestic trophies is a tremendous achievement and that is testament to the real focus and relentlessness of the manager, the players and our whole backroom team who have all worked so hard," Celtic captain Callum McGregor said of Postecoglou on his departure.
"We have delivered something very special to our fans and done it, under the manager's direction, by playing an exciting and attractive brand of football. As all the players do, I wish Ange great success in his next challenge."
Postecoglou will take charge of Spurs on July 1, with some of his first few days with the club taking place in familiar surroundings as they begin their pre-season with a game against West Ham in Perth, Australia.