What does future hold after Celtic turn to the past?

If you were to turn up at Celtic Park today you might not be surprised to see a DeLorean parked outside the big glass front door.

It may be the 40th anniversary of the iconic Back To The Future film franchise in cinemas, but it's the Scottish champions who are choosing to dabble in some time travel with Martin O'Neill back as interim manager after Brendan Rodgers' shock resignation, 20 years after he ended his first spell in charge.

The unseemly fallout between Rodgers and Dermot Desmond spilling into the public domain via Celtic's biggest shareholder's statement was so box office it sucked up most of the oxygen in the wake of Monday's news.

But now the question that should actually matter to Celtic supporters is not who to side with, but what is next for the club?

The initial statement from Celtic on Monday was Rodgers had resigned. Then came the statement from Desmond, reiterating this, while also launching a broadside at the former manager.

It was the first illustration of retaliation from the upper echelons of the club to a public narrative from Rodgers.

Since the summer, the now former Celtic manager has been repeatedly asked about - and answered - the lack of transfer activity, and also the quality of those who were actually brought in.

How did the transfer window leave Rodgers feeling? "Empty" he told his press conference on 12 September.

In that same media opportunity, he went on to speak of "cowardly" actions from a club insider who told a newspaper he was trying to manufacturer an exit.

He also waxed lyrical regarding his "huge respect" for Desmond.

The need for support in his team was clear: Kyogo Furuhashi and Nicolas Kuhn were both sold, while Jota's return has been marred by a long-term injury.

This has been compounded by new players struggling to make an impact, plus injuries to key players.

Only three summer recruits started the defeat by Hearts on Sunday.

The result? A pretty limp opening to a disappointing campaign. Eight points off leaders Hearts with points dropped in four games, and out of the Champions League while not scoring a goal against Kazakhstan side Kairat Almaty in a play-off.

Rodgers heavily laboured the standard of his squad, and the disappointment at not getting the quality he wanted in the transfer window.

Fine, but it's undeniable his team have been nowhere near their optimum level under his recent stewardship.

Only in February Celtic were seconds away from a famous win in the Champions League. They were 1-0 up against Bayern in Munich, with extra time beckoning until a 94th-minute Alphonso Davies aggregate winner.

Since that night, Celtic have played 31 games. They've failed to win 14 of them, including surrendering a Scottish Cup final lead against Aberdeen.

Transfermarkt, external lists the Parkhead squad to be worth £115m. To put that into context, league leaders Hearts are valued at just above £16m.

The Dundee squad who convincingly beat Celtic would cost you just £6m, apparently.

So though Rodgers and many Celtic fans would argue the squad is far weaker than last season, especially in attacking areas, more is still expected of this group.

Just like Celtic turned to a familiar face in Rodgers when Ange Postecoglou left for Tottenham, they've done so again in O'Neill, albeit only as an interim option.

Revered as one of the most popular managers in the club's history, he will be flanked by his former midfielder Shaun Maloney in the home dugout on Wednesday when promoted Falkirk visit Celtic Park.

It will be a surreal scene for all inside the ground, none more so than O'Neill himself.

On Tuesday he told of how he had to "pull myself up off the floor" when the call came to step into the breach and had 10 minutes to decide.

The 73-year-old boasts the highest win percentage of any Celtic manager, and he was agonisingly close to adding two further league titles to the three he claimed as well as a Uefa Cup final appearance in 2003.

Names such as Craig Bellamy, Kieran McKenna and even Postecoglou are already being mentioned as a replacement long-term for Rodgers.

O'Neill has stressed this is short term, nothing more. The grand reception he will undoubtedly get on a cold Wednesday night in Glasgow may warm his heart, but it is results the club needs right now, not romantic nostalgia.

Victory against Falkirk is surely a must for supporters, with a section of the fanbase having been actively protesting against the club's board and a further demonstration planned.

After that, it is a Premier Sports Cup semi-final with Rangers on Sunday at Hampden.

It is quite an incredible scenario where the two managers in the season's first Old Firm meeting will not be there for the second just two months on.

It is the first time in their history that both clubs have parted company with their manager in the same campaign.

There is a real chance that by the time the third Old Firm match is played at new year, it will be a third man in the Celtic dugout.

But it is not about the past or the future for the players, it is about the here and now.

The immediate job for O'Neill and Maloney is to lift the storm clouds and change the narrative. Two victories in their next two games would undoubtedly do that.

What happens beyond that, you will need to jump in that DeLorean to find out.