Rangers vs Celtic: Gary McAllister and Ange Postecoglou look ahead to Sunday's Old Firm match at Ibrox

Rangers will take Covid-19 guidance before they know who will be available for Sunday's Old Firm clash against Celtic, according to Gary McAllister.

The champions' preparations for the Ibrox showdown have been hampered after manager Steven Gerrard and six players were forced to self-isolate following an unknown number of positive tests at the club.

Assistant McAllister led a threadbare Rangers side through to the Europa League group stages on Thursday and while he is unsure if those who missed the second leg against Alashkert will be back to face Celtic - he is expecting others to return.

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"We will just deal with this day-by-day and are being guided by the governing bodies," he said.

"Whoever is available on the day will get on with the job. I am in constant contact with the manager and we will be bolstered with some players coming back from suspension and niggling injuries.

"There are three non-squad players available, (Juninho) Bacuna, (Brandon) Barker and (Nikola) Katic - so there is a bit more strength & depth when we get back to Glasgow.

"It is a massive game and a game that every player would love to play in, whether you've played with the Old Firm or are watching from the outside - it catches the imagination.

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"The intensity of the game and build-up to the game is big. We have a group of players here who are looking forward to it because it is a game for big players to produce moments.

"Generally, these games can be decided on a mistake or set-piece but it just demands such serious concentration and focus so that's what I'll be asking the players if I'm in charge - just be concentrated and focused for the job at hand."

Postecoglou promises respect at Ibrox

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The match will be Ange Postecoglou's first taste of an Old Firm clash and he has warned his players to expect a "great test" on Sunday, irrespective of who Rangers field.

"If you start thinking it is going to be some sort of an easier game because of disruptions they've had or disruptions we might have then you fall into a false trap," he said.

"What we do know is that whatever the line-up is on Sunday they are going to be a formidable opponent.

"One thing we'll never do is not respect an opponent irrespective of the build-up to a game, particularly a big game.

"What you know is that for both sides, both sets of 11 players, you start that game and you're up for a big game and you're concentrating on yourselves."

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Celtic recovered from defeat at Hearts and a Champions League exit by reaching the Europa League group stages and sealing consecutive 6-0 wins in the Scottish Premiership.

Another major test awaits on Sunday against the champions but the Australian stressed the game would not decide anything.

"It's August," he said. "I know people like putting defining moments in at all different times. There will be defining moments all throughout the season.

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"What's important is we have had a really positive month so far and in terms of improvement in our performances and getting reward for that. Sunday is another opportunity to build on that momentum for us.

"It's the end of August and there is still a hell of a lot of football to be played. And from our perspective, either way, we are not going to get too carried away with whatever the outcome is.

"We want to continually improve our performances and Sunday is a great chance for us to establish our football against a very good opponent in a difficult environment. What a great test it's going to be for us."

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