Moussa Dembele is the first Celtic player into the book with a late challenge on Fabio Cardoso as they challenge for a header.
Former Scotland striker on BBC SportsoundQuote Message: Scott Brown's doing a brilliant job just now - he's really snuffing out danger. Anything that comes into the box, he's first on to it to clear
Sean Goss has not covered himself in glory in Rangers' midfield and the on-loan QPR man is hauled off and on comes Jason Cummings.
The on-loan Nottingham Forest striker was perhaps unlucky not to start considering his hat-trick last weekend.
Former Celtic goalkeeper on BBC SportsoundQuote Message: Rangers allowed Edouard to come back on to his right foot. Goss has got to push him down the narrow side, don’t let him come inside, where it opens up the goal. But it’s a brilliant finish from Edouard, bending it round the goalkeeper. And I’ve got to also say, the pass from Dembele was great to set him free
What a couple of minutes. Alfredo Morelos misses a great chance to put Rangers ahead and Celtic race up the other end and take the lead.
Brendan Rodgers will be hailed for that substitution as Moussa Dembele sets up Odsonne Edouard, who steps inside Sean Goss and curls a drive into the far corner from 16 yards only a couple of minutes after entering the fray.
Dedryck Boyata is at fault again as the defender fails to make contact with an interception attempt and Alfredo Morelos charges forward .
The striker's powerful drive is parried clear by goalkeeper Scott Bain after a slight deflection off Kristoffer Ajer.
Rangers are beginning to ramp up the pressure on the 10 men of Celtic.
Yet Celtic manager Brendan Rodgers replaces winger James Forrest with striker Odsonne Edouard. That looks like a positive one considering he now has two strikers on despite being a man down.
Rangers have a chance to put pressure on Celtic as Scott Brown trips Josh Windass, but the midfielder's free-kick is well over the crossbar.
Former Celtic goalkeeper on BBC SportsoundQuote Message: I'm surprised Rogic is coming off because he's a big player, he's scored a goal. I know he's just coming back to fitness, but he can create something out of nothing. Of course, now a draw would be a good result for Celtic
Celtic manager Brendan Rodgers sacrifices scorer Tom Rogic as he replaces the Australian midfielder with Jack Hendry, the central defender who was signed from Dundee in January.
Former Scotland striker on BBC SportsoundQuote Message: I don’t think it’s intentional. Simunovic is looking at the ball. But it’s a definite elbow and he’s definitely caught him
Celtic are down to 10 men and Jozo Simunovic can have no complaints as the central defender lands what looks like a deliberate elbow into the chin of Alfredo Morelos.
MP Douglas Ross, the referee's assistant, appears to be the man to have made the decision.
Celtic continue to look the more dangerous, with Rangers relying on a high pressing game and breaking quickly, but the home side are showing nothing creative in the centre of the park.
Indeed, they are by-passing midfield.
Former Celtic goalkeeper on BBC SportsoundQuote Message: In the modern game, that could be a sending off. He's not even going for the ball. He's absolutely taking the player straight out of it. It was really cynical
Fabio Cardoso is the second Rangers player to be booked for an ice hockey-style take out of Moussa Dembele.
Former Scotland striker on BBC SportsoundQuote Message: It’s not a penalty. That’s brilliant refereeing from Willie Collum. Callum McGregor had lost his balance and falls and it’s top refereeing
Celtic are on the front foot again and Callum McGregor goes down inside the box under a Greg Docherty challenge.
Muted cries for a penalty are ignored by referee Willie Collum and, in truth, Docherty's challenge began outside the box and McGregor looked to lose his footing anyway.
Rangers get the second half under way.
Could we see another four goals?
The teams are back out after a well-earned breather.