Celtic manager Martin O'Neill tells BBC Sportsound: "Big match for us tonight.

"Concerned about the game because St Johnstone are playing so well at the minute. They've shown their mettle. It'll be a tough test for us. They're comfortable with the ball, they want to play.

"[Cameron] Carter-Vickers had played every single game. The last stages of the game on Saturday night, I thought he was wilting, just feeling a little bit sore. I thought the best thing to do is just leave him out completely.

"[Camilo] Duran, [Benjamin] Nygren, who have scored big, big goals, don't start but I'm quite sure they'll be on the field at some stage or another.

"[Viljami] Sinisalo has done really well, taking over from Kasper [Schmeichel] last season. We've got a lot of games. It's a chance what to see what [Sam Johnstone] is capable of doing."

Asked about his first return to the McDiarmid Park in 25 years, O'Neill said: "It feels 25 years, there's definitely no question about it."

Image source, SNS

Rory Loy
Former Rangers striker on BBC Sportsound

I think Naderi is industrious, but he is a bit scruffy, a bit hash and bash.

I am not sure he has the quality of strikers gone by and being a Rangers player.

Given the injuries, it is a huge time for him to come in.

Andy Burke
BBC Sport Scotland

With fellow striker Youssef Chermiti expected to be out for a lengthy period after suffering anterior cruciate ligament damage, Lawrence Shankland's absence comes at a particularly bad time for him and for Rangers.

"Having [Shankland] and Youssef out, two guys that guarantee you goals at Premiership level, there's no doubt it's a blow for us," manager Derek McInnes said.

Rangers were good value for their win over Motherwell, but with the number of chances they created it should have been more comfortable.

Ryan Naderi is yet to convince since joining last winter, even after scoring a winner that was gifted to him on Saturday.

The only striker on Rangers' books whose stats compare favourably with Shankland is Bojan Miovski, but the former Aberdeen favourite has found it difficult to get a consistent run in the side.

Big-money signing Kevin Kelsy had a golden opportunity to announce himself on his debut against Motherwell but showed little composure as his shot clipped the crossbar on its way out.

Of course, it is far too early to rush to judgement on Kelsy's ability to fill the Shankland void, but 13 goals in his past 46 games would suggest the Ibrox club have not signed an out-and-out scorer.

It seems like a legal requirement now that Celtic need to have an over-30-year-old former Premier League goalkeeper between the sticks.

Fraser Forster. Joe Hart. Kasper Schmeichel. Now Sam Johnstone is the latest to join that club.

The big man has been showing off his flexibility pre-match.

Image source, SNS

The next 11 days could prove to be crucial in Celtic's season. The same could be said for Rangers, too.

Following tonight's action, Martin O'Neill's side face two derby meetings against their city rivals, either side of a Europa League opener with Ferencvaros.

O'Neill's men are on the road again on Sunday when they make the short trip to Govan, but the manager would not allow himself to be distracted by the League Cup quarter-final and insists tonight's game holds more significance.

The 74-year-old said: "I genuinely can't [have one eye on it] and that's honestly where I think, first of all, we have to play our game.

"We have to try and defend a title. We have to try and win a football match.

"And to me, this game is far more important than Sunday's match."

Here's how the table looks heading into tonight's rearranged fixtures.

Celtic lead the way with five wins from five, with Rangers three places and five points behind their rivals at this early stage.

St Mirren are level on points with the Ibrox side and are above them only on goal difference, while St Johnstone will be hoping to move into the top half with a positive result in Perth.

Andy Halliday
Former Rangers midfielder on BBC Sportsound

Craig McLeish's side have been a sight for good eyes this season.

The real disappointment for them has been that game here in the Premier Sports Cup and losing heavily 5-1. Will they take the same approach?

Since Rangers have stumbled on the 4-2-3-1 system, it has really suited them.

Will they return to the 4-4-2 that came with heavy criticism?

BBC Sounds

Pre-match coverage is under way on Sportsound, plus you'll have a choice of listening when the action starts.

Choose between live match commentary from Ibrox or McDiarmid Park, then the team will provide post-match reaction.

Take your pick on this very page.

St Johnstone hand a debut to on-loan Hibernian midfielder Josh Campbell in one of four changes.

Joel Cotterill, Daniel Finlayson and Matty Todd also come in.

Attacker Jamie Gullan is out with a minor groin issue, Zach Mitchell also misses out and Liam Smith and Sam Stanton drop to the bench.

Celtic make five alterations to their starting XI, including one in goal.

Loan keeper from Wolves, Sam Johnstone, replaces Viljami Sinisalo, who makes the bench, while at the back Dane Murray takes over from Cameron Carter-Vickers, who is not in the squad.

Oliver Sorensen makes his first club start in midfield while Kasper Hogh and Sebastian Tounekti join the attack.

Camilo Duran and Benjamin Nygren drop to the bench, which includes Kieran Tierney, while South Korea winger Yang Hyun-jun is absent because of the Asian Games.

Image source, SNS

Image source, SNS

Derek McInnes has shifted his Rangers formation to 4-4-2 and thrown in new signings Kevin Kelsy and Badredine Bouanani for their first starts.

The third change to the starting line-up following Saturday's win over Motherwell sees Ryan Naderi come into the attack to partner Kelsy.

Lawrence Shankland is out for up to four months with a hamstring tear, while Findlay Curtis and Kim Min-su drop to the bench.

The only St Mirren switch after their defeat to Celtic on Saturday night is centre-back Louis Jackson coming in for his debut to replace Paul Nsio, who is ineligible to play against his parent club.

That should mean Alex Gogic moves into the visitors' midfield.

St Johnstone: Stewart, Finlayson, Alic, Diabate, Todd, McAlear, Cotterill, Steven, Holt, Campbell, Fowler.

Substitutes: Sinclair, Boyes, Stanton, Foulds, Fotheringham, Schmidt, Tait, Smith, Paton.

Celtic: Johnstone, Donovan, Murray, Trusty, Scales, McGregor, Sorensen, Baur, Hassan, Hogh, Tounekti.

Substitutes: Sinisalo, Lotomba, Nygren, Duran, Oxlade-Chamberlain, Mheuka, Van den Berg, Forrest, Tierney.

Rangers: Pandur, Sterling, Fernandez, Makhanya, Penrice, Neil, Raskin, Bouanani, Gassama, Kelsy, Naderi.

Substitutes: Kelly, McCrorie, Godfrey, Dragojevic, Devlin, Chukwuani, Curtis, Kim, Miovski.

St Mirren: Chapman, Ramsay, Jackson, Fieldson, John, Gogic, Carr, Taylor, Kabia, Mochrie, Agrafiotis.

Substitutes: Mullen, Richardson, King, McEvoy, De Barros, Thomas, Farquhar, Young, Sule.

Apparently the Champions League is on tonight. No thanks.

Our focus is firmly on the Scottish Premiership as Rangers host St Mirren (19:45 BST) and Celtic travel to St Johnstone (20:00)

Some very interesting team news has dropped at both grounds.

Let's not wait about any longer.