WHAT a difference a year makes. At this stage 12 months ago, there was as much trepidation as there was anticipation among the Celtic supporters ahead of the new Premiership campaign, and – initially at least - with good reason.

The hitherto little known Ange Postecoglou – on this side of the world, anyway - had a massive job on his hands. In all respects.

He was immediately tasked with rebuilding a squad of players and lifting those who remained off the floor after the disastrous season that preceded his arrival. A Champions League qualifying exit to FC Midtjylland may have been expected due to the tumult of the time, and an opening day Premiership defeat to Hearts at Tynecastle – one of three losses in their first six league matches – hardly hinted at what was to come.

Slowly but surely though, Postecoglou managed to mould the raft of new arrivals he had brought to the club into a cohesive unit, and more than that, a slick, exciting outfit that were proving difficult for Scottish opponents to handle.

Postecoglou would win his first domestic trophy at the first attempt, as a double from the new darling of the fans, Kyogo, saw off Hibernian in the League Cup final at Hampden in December, but his side remained stretched, and an injury crisis left his men somewhat limping into the winter break.

Down to the bare bones and trailing Rangers at the top of the table, the January transfer window took on huge significance, and just as he had in the summer, Postecoglou got his recruitment spot on.

The Japanese trio of Reo Hatate, Daizen Maeda and Yosuke Ideguchi were immediately brought in, and Hatate and Maeda would play pivotal roles as Celtic reeled in and overtook Rangers at the top of the table, while the capture of Matt O’Riley from MK Dons proved a bargain, and helped compensate for the loss of David Turnbull to injury.

Indeed, it would be Hatate who would play a starring role in the week that Celtic hit the top of the standings. A late Liel Abada goal against Dundee United gave Celtic the opportunity to move ahead of Rangers with a win in their next match in early February, and they duly blew their rivals off the Celtic Park pitch to seize their opportunity.

A stunning Hatate double and another from Abada before the break left Rangers in their wake, and Celtic never looked back, eventually sealing an unlikely title with a draw at Tannadice on the second-last day of the season.

A defeat to Rangers in the Scottish Cup semi-final was the only domestic black mark against Postecoglou’s team in the second half of the campaign, but at least that leaves a little room for improvement heading into next season.

Where Postecoglou will certainly be looking for more from his team is in European competition, following up their Champions League qualifying exit last term by crashing out of a tough Europa League group stage in third place behind Real Betis and Bayer Leverkusen, before a disappointing exit from the Conference League to Bodo/Glimt.

Their title win afforded Celtic the luxury of a pass straight into the Champions League group stages this time around, so the challenge for Postecoglou this summer has been not only to further enhance and develop his squad to retain their Premiership crown, but to ensure they can compete against the best sides that the continent has to offer.

As a pot four team, the odds are stacked against Celtic, but if he can make a fist of finishing in third place in the group and ensure a spot in the knockout stages of the Europa League, that would have to be classed as a success.

To that end, Postecoglou has added some experience to his ranks during this window, with the arrival of 31-year-old midfielder Aaron Mooy – a player he knows well from his time in charge of the Australian national side – seen as a slight concession that Celtic will need to tighten up at least a little when facing sides at the very top level.

As well as Mooy, Ben Siegrist has come in to provide cover for Joe Hart, Moritz Jenz has added depth to the backline, while £3.75m was spent on bringing in attacking left-back Alexandro Bernabei from Lanus.

Perhaps the most important business done by Postecoglou though was the permanent signings of defensive rock Cameron Carter-Vickers and winger Jota from Tottenham Hotspur and Benfica respectively after star turns on loan last season.

The Celtic fans are somewhat unsurprisingly looking forward to flag day against Aberdeen on Sunday and the rest of the coming season with feverish excitement, and it will be up to Postecoglou and his men to meet the rising expectations that are the result of their success to this point.

NEED TO KNOW - CELTIC

Manager: Ange Postecoglou

Captain: Callum McGregor

Key Player: Callum McGregor. The influence of the Celtic skipper cannot be underestimated, and while other, flashier players may hog the limelight, he is perhaps the one irreplaceable man in Postecoglou’s starting XI.

Kyogo will be vital of course, but the emergence of Giorgos Giakoumakis in the second half of last season compensated for his absence through injury.

An argument could certainly be made that the defence would be in bother without the presence of Carter-Vickers, but the arrival of Jenz may solve that particular problem.

McGregor is the man who makes Celtic tick, and remains their most important player.

Ins: Alexandro Bernabei (Lanus), Cameron Carter-Vickers (Tottenham Hotspur), Moritz Jenz (FC Lorient), Jota (Benfica), Daizen Maeda (Yokohama F. Marinos), Aaron Mooy (Shanghai Port), Ben Siegrist (Dundee United).

Out: Conor Hazard (HJK Helsinki, loan), (Adam Montgomery (St Johnstone, loan), Liam Scales (Aberdeen, loan), Ismaila Soro (Arouca, loan), Osaze Urhoghide (KV Oostende, loan).

Last season: A pleasant surprise. Ange Postecoglou confounded the doubters by making an immediate impact, recruiting shrewdly and whipping his side into high-intensity title winners. The League Cup followed, and if the Australian can deliver a Treble and European football past Christmas, they may well be planning the statue on The Celtic Way already.