Celtic: What is on new manager Ange Postecoglou's to-do list?

It took 106 days, but Celtic have finally appointed a new manager in Ange Postecoglou. Now the sizeable task of reviving the deposed Scottish champions begins.

The former Australia boss succeeds Neil Lennon at a club in transition following the end of their nine-year title dominance and 12 successive domestic trophies.

Here, BBC Scotland assesses what awaits in the 55-year-old's packed in tray.

Postecoglou is now in situ as the centrepiece of the huge shake-up at Celtic, which has also seen Dominic McKay arrive from Scottish Rugby as chief executive, with Peter Lawwell ending his 17-year tenure this summer.

But another key appointment - the technical director role Postecoglou will be closely aligned with - has yet to be made. That position became vacant when head of football operations Nick Hammond departed in late March to "pursue new opportunities".

Fergal Harkin was the prime candidate to fill the position. The Irishman is football partnerships and pathways manager at Manchester City, whose stable of clubs includes Yokohama F Marinos, from where Postecoglou has arrived. But after being strongly linked with Celtic, Harkin has opted to stay, external with the English champions.

Former Celtic striker Shaun Maloney has reportedly had talks with the Glasgow club over a key strategic role, while John Kennedy can't be discounted as Celtic neglected to mention whether the former interim boss will be part of the new set-up.

Having taken so long to find a new manager - turning to Postecoglou after a lengthy pursuit of Eddie Howe collapsed - Celtic need to quickly provide the Greece-born Australian with the necessary support structure.

Should Kennedy and first-team coach Gavin Strachan remain part of the staff, however, it would be a bone of contention among the fan base following the pair's part in last season's failure.

One of Postecoglou's first tasks will be establishing just how many players he has to work with. Long-serving captain Scott Brown has already moved on to Aberdeen and the future of integral first-term trio Odsonne Edouard, Kristoffer Ajer and Ryan Christie will be uppermost in the new manager's thoughts.

Prolific France Under-21 striker Edouard - Celtic's record signing at £9m - Norway centre-back Ajer, 22, and 26-year-old Scotland forward Christie are all into the final 12 months of their contracts.

Edouard in particular is not short of European suitors, while Ajer has voiced his desire to leave, external, and Christie may fancy an opportunity elsewhere, with Euro 2020 offering a chance to showcase his abilities.

Then there's the churn of loan signings to deal with. Shane Duffy, Jonjoe Kenny, Diego Laxalt and Mohamed Elyounoussi have all returned to their respective clubs, with six Celtic players heading back to Glasgow.

Of those, striker Vakoun Issouf Bayo and winger Marian Shved were so far out of the picture it's difficult to envisage them forcing themselves into Postecoglou's plans.

Midfielder Ewan Henderson may be bracketed as one for the future, but could the clean slate of a new manager allow Scotland centre-back Jack Hendry, French midfielder Olivier Ntcham or Belgian left-back Boli Bolingoli the chance to resurrect their Celtic careers?

And Brown's departure means there is also a new club captain to be appointed, with understudy Callum McGregor the leading candidate, assuming he is not the target of interest from elsewhere.

Postecoglou could well be left with a decimated squad - albeit with a decent budget at his disposal - heightening the importance of getting his recruitment right.

Surgery is required right through the team and Postecoglou said at his unveiling that "we have already begun work on our plans for adding to the squad".

Of the three goalkeepers on the books - Vasilis Barkas, Scott Bain and Conor Hazard - none have made a convincing case to be the long-term incumbent.

And the defence is effectively a start from scratch job. Fringe player Anthony Ralston is the only right-back signed beyond this summer, while Greg Taylor is the sole left-back unless Bolingoli stays.

Central defence needs to be significantly strengthened, especially if Ajer is sold. Christopher Jullien's long-term knee injury could potentially keep the Frenchman out until November, meaning converted midfielder Nir Bitton and 21-year-old Stephen Welsh are the only fit and available options.

Midfield is better stocked and could be the foundation of Postecoglou's team. Ismaila Soro has proved himself capable of inheriting Brown's holding role and David Turnbull enjoyed a fine first season despite the team's struggles.

The return from injury of wingers James Forrest and Mikey Johnston bolsters Postecoglou's hand, as does the arrival of versatile midfielder Liam Shaw on a pre-contract from Sheffield Wednesday, although further strength in depth will be required.

Up front presents a conundrum for the new manager, who will be pondering how to replace the goals and guile of top scorer Edouard should the Frenchman depart as expected.

Of the other strikers, doubts hover and one has already gone, with Patryk Kilmala sold to New York Red Bulls. At £5m, Albian Ajeti may be too expensive to write off after an underwhelming first campaign and could thrive under fresh management.

Leigh Griffiths, now 30 and having spent last season on the periphery amid fitness issues, may find himself surplus to requirements.

While his squad takes shape, Postecoglou has to implement his style of play and get his ideas across on the training pitch.

A number of players regressed last season as Lennon's reign fell into a tailspin, and Postecoglou's hands-on approach to coaching made him an attractive choice. So too his demands of a fast-paced, attacking and possession-based style.

Postecoglou aims to "make sure our supporters don't sit down for 90 minutes" and says he is a "big believer" in bringing through talent from the youth system to the first team.

However the new era unfolds, it will be anything but dull. Time is a luxury not afforded to the Australian though, with Celtic's season kicking off in the second round of Champions League qualifying in just six weeks.

And when the competitive action starts, the mandate for any Celtic manager is simple - win and keep winning. His successor Lennon, speaking to BBC Radio 5 Live recently, emphasised the need for a smooth start.

"Whoever goes in will have a blank canvas," Lennon said. "The magnitude of Celtic and expectation of the supporters, you have to hit the ground running. But it's a great challenge and a very exciting period."