THE Old Firm fixture has been central to so many aspects of Alan Thompson's career it is surprising that he can dismiss the prospect of it possibly not existing beyond the summer with barely a second's thought.

As a Celtic player, Thompson enjoyed mixed fortunes in the Glasgow derby matches, netting winning goals, being sent off in others. It has been similarly tumultuous since he became part of Neil Lennon's backroom staff almost two years ago. Big games have been won and lost, there have been touchline tantrums and run-ins with officialdom. It has never been dull.

Rangers' financial worries mean there is a chance that tomorrow's appearance of Scottish football's twin-headed monster could be the last for quite some time. Were the Ibrox club to be liquidated and a newco to start life in the third division – hard as that is to imagine – then it could be quite some time before the teams were to meet again in competitive action.

That scenario will bring ramifications that go far beyond just the Old Firm but, given it is the game most Celtic and Rangers fans look forward to, it would leave a gaping hole in the lives of everyone with an attachment to either club. Or so you might think.

Thompson, though, was not for getting misty-eyed about the prospect of a Clydesdale Bank Premier League campaign without visits to Ibrox, or Rangers coming to Celtic Park. He gave a straightforward "yes" when asked if he could imagine a scenario where there are no Old Firm games on the calendar, and insisted that Celtic's plans for the future would not be shaped in any way by what goes on across the city.

"We can't afford to get involved in that," he said. "Celtic are going to carry on regardless. So that's not our problem. Rangers have their own problems to deal with. That's been coming their way. It's not going to affect how we approach the summer or approach pre-season. You would have to ask Peter Lawwell [Celtic's chief executive] about budgets and stuff, but we'll still be approaching the Champions League qualifiers as we would have done, regardless of what was happening with Rangers."

Thompson knows his history and is grateful to have been part of a club run prudently and efficiently in recent times. "I can only speak about what I have found since I came here in 2000. The club has been run very well in that time. People know better than me about the problems Celtic had before Fergus McCann came and waved his wand. So Celtic have had their problems but, for the past 15 years or so, it has been run very well as a football club and a business."

Rangers continue to fight off the threat of liquidation but, regardless of that ongoing attempt to keep the club alive, there is a growing feeling around Glasgow that tomorrow's Old Firm derby could come to represent a historic landmark, given there are no guarantees the fixture will definitely return next season.

Neither side has anything significant to play for – Celtic have already been crowned champions, while Rangers cannot play in Europe next season regardless of where they finish in the league table – but that will do little to detract from a fixture that is combustible regardless of what is at stake.

"I've played in enough and been involved in a few as a coach, so it's not meaningless for us and I'm sure it won't be for the Rangers boys," insisted Thompson. "It's a great feeling to win any Old Firm game, so Sunday is one that we're going to approach the same as always.

"You don't want to rub salt in people's wounds but we want to win the game, and they'll come with pride and want to try to win the game. It's the last big occasion of the season for us. We've three games left, we've got the presentation of the trophy to look forward to, but in terms of games this is the biggest one by a mile."

A Celtic victory would put them 21 points clear of their biggest rivals – 11 with three games to go if Rangers' 10-point deduction is taken out the equation – and should put to bed once and for all talk of a tainted title. "It would be great to go 21 points clear, or 11, whichever way you want to look at it," said Thompson. "Come the end of the season it would be nice to win the league by more than 10 points."

Referee Calum Murray sent Lennon to the stand and dismissed three players – Cha Du-Ri, Victor Wanyama and Carlos Bocanegra – in the last Old Firm game a month ago, but Thompson has no problems with the same referee taking charge tomorrow following the late withdrawal of Craig Thomson.

"I've no reservations at all about that. I like Calum, I've got a lot of respect for him and think he's a good referee. I thought that before the last Old Firm game and I haven't changed my opinion since then. We're fairly pleased, even though he has got two in less than a month."