Rangers' return breathes life back into Scottish football - but don't call it Old Firm
Around Celtic Football Club, the first rule of the modern Old Firm rivalry is to ensure that you do not talk about an Old Firm.
Tomorrow, the SPL champions will take on Rangers in the semi-finals of the Scottish Cup, and a good portion of the overseas audience which tunes in will doubtless refer to the fixture by that moniker.
You won't find that term in the official Celtic coverage of the fixture, however, a detail which might come as a surprise to the casual punter who is paying attention to Scottish football again now that Rangers' promotion to the top flight is confirmed. The release of the 2016/17 fixture list will be all about the derby dates. Normal order will be restored.
Celtic fans claim that when Rangers were liquidated in 2012 and forced to start at the bottom of the Scottish league ladder as a new trading company - Sevco - the traditional terms of reference died with them.
Before the sides met in a League Cup game last year, a collection of Hoops followers took out an ad in a Scottish Sunday newspaper which read: "As Celtic supporters, we regrettably recognise that our club had an association with Rangers (1872) through the collective description, The Old Firm. We believe this term is now redundant - this will be the first ever meeting between the two clubs."
They will argue, and not without foundation, that the £55m debt left to creditors by the original Rangers trading company casts a shadow over the trophies they won in the period before they went bust.
But, in reality, the declaration that the Old Firm is over is repeated gleefully because it winds up their city rivals and reminds them of the misery that accompanied their dramatic fall from grace.
It's all part of a pantomime that has found renewed energy on social media and the Celtic hierarchy are clearly happy to roll with it. Interviews with a range of squad members on the official website this week all made reference to the 'Glasgow derby'.
A gathering of Scottish journalists were amused recently when a member of the management team corrected himself mid-flow when he was halfway through saying 'Old Firm' in a sentence before getting back on message.
Nevertheless, the scramble for tickets for tomorrow's encounter at Hampden Park has proved that the Rangers brand, whatever version this may be, is the biggest draw for Hoops followers.
Run-of-the-mill league games are failing to capture the imagination as Ronny Deila's side chug unconvincingly towards the inevitability of another league title despite the best efforts of Aberdeen.
Make no mistake about it: Celtic are a huge club and consistent crowds upwards of 30,000 compare favourably with English and European standards. Still, their average turn-out has fallen in recent years, with the top tier of Celtic Park frequently closed. Even the season tickets holders are picking and choosing their outings.
Chief executive Peter Lawwell highlighted the cost of Rangers' absence, saying: "When Rangers went down, we took £100 off season tickets. So that is £4m for two years.
"The Rangers games, at least, (were worth) another £3m. Then there's a perception among our supporters that there is no competition, you are going to win anyway and you don't go to the game. So it could be £10m."
At that juncture, he argued that Celtic had covered the shortfall by performing well on the field and minding the finances off it but dreadful European results under Deila have posed serious questions about the ambition of the business plan.
The spectre of a challenge from Rangers could prompt decisive action. Privately, players and staff admit they have missed that edge, even if the last set of games before Rangers imploded - featuring sideline showdowns between Ally McCoist and Neil Lennon - were particularly toxic and led to grandstanding politicians asking if all the hassle was really worth it.
It's box office though, and a major source of interest this summer will be the behaviour of Rangers in the transfer market ahead of their top flight comeback.
As it stands, Mark Warburton's squad are some distance behind Celtic in terms of quality - they made headlines in January by swooping for two players from Accrington Stanley - and this weekend could advertise how far they are behind. Without investment, they will not get near Celtic next term.
A title fight between the pair would help to put Scottish football back on the map.
Earlier this week, former Rangers boss Graeme Souness said that the English public had no real interest in affairs north of the border. "People used to speak about it but not any more," he said. "The interest has diminished.
"All the people who rejoiced in Rangers' demise had such a short-term attitude, a really parochial view of it. Look at Fraser Forster, Virgil van Dijk and Victor Wanyama? Do Celtic really sell those players if Rangers are still challenging? They've sold some of their players, which means supporters turn up to see not such a good Celtic team.
"That's shown itself in the numbers who turn up. They are not enjoying what they're seeing. If Rangers were strong, Celtic would have to be stronger."
In Ireland, there remains a fanatical base of Celtic fans who travel across on a consistent basis, but they tend to be pigeonholed as a niche market in the podcast-driven football culture that increasingly focuses on other leagues around Europe as the alternative to the Premier League.
During the mid-90s and the early 2000s, the Glasgow pair were part of that discussion as they housed some of the continent's best players and featured at the business end of UEFA's marquee competitions.
Henrik Larsson and Brian Laudrup could have played for any number of Europe's top clubs while they chose to ply their trade in Scotland.
Together, the Big Two negotiated TV deals which strengthened their position and allowed them to recruit quality personnel. They often found themselves batting against the other SPL clubs amid persistent talk of a breakaway to England. Joint 'Old Firm' statements were not uncommon.
The dynamic has changed somewhat, but the inescapable conclusion is that they need each other more than ever.
A cup semi in a season which both parties started with other priorities is a warm-up for the interesting road that lies ahead. Celtic v Rangers always matters to the protagonists, but this is another step towards making their domestic squabbles relevant again.
Rangers v Celtic, Sky Sports 2, tomorrow 12pm