It took just four minutes for the latest Old Firm derby to explode into life.
Before either side had properly settled into the contest, Derek McInnes was already involved in a furious touchline confrontation after Rangers defender Manny Fernandez was shown an early yellow card for bringing down Camilo Duran.
For McInnes, the decision was apparently too harsh for a first foul so early in the game.
The Rangers manager immediately made his feelings known to the fourth official before the situation spilled over towards the Celtic dugout.
And within moments, the intensity of the match had moved from the pitch to the touchline.
McInnes was seen gesturing with his fingers, appearing to indicate that Fernandez had only committed his first foul of the afternoon.
But the Rangers boss’ frustration soon brought him face-to-face with Celtic first-team coach Mark Fotheringham.
The two exchanged words before Martin O’Neill intervened, stepping between them as tempers threatened to escalate further.
Referee John Beaton eventually brought the situation under control by showing both McInnes and Fotheringham yellow cards.
It was another chapter in an already tense relationship between McInnes and Fotheringham, who had previously clashed when McInnes was in charge of Hearts during a meeting with Celtic earlier this year.
And with this being the second Old Firm meeting between the teams in the space of just seven days, there was never likely to be much room for calm.
Rangers strike first at Celtic Park

Despite the touchline drama, the attention eventually returned to the football.
And it was Rangers who delivered the first major blow.
Ryan Naderi put McInnes’ side ahead in the 33rd minute, reacting quickest after Dan Neil’s effort was not held by Celtic goalkeeper Viljami Sinisalo.
The goal was another significant moment for Naderi after his injury scare during the previous Old Firm meeting.
Rangers had been concerned that the striker could miss Sunday’s game after the Mika Baur challenge left his ankle in poor condition.
McInnes had described the ankle as “a mess” and confirmed that Rangers had contacted the Scottish FA regarding the incident.
Yet Naderi recovered sufficiently to start at Celtic Park.
And he ended up making the difference.
The striker’s finish silenced a Celtic Park crowd that once again had no travelling Rangers support inside the stadium because of the ongoing restrictions on away fans.
Rangers entered the match having already beaten Celtic 3-0 at Ibrox in the League Cup just a week earlier, and Naderi’s goal gave them another advantage in the second meeting.
More Old Firm controversy after the break
The drama did not end with the opening goal.
Rangers thought they had doubled their advantage when Olwethu Makhanya smashed the ball into the net.
The celebrations, however, were short-lived.
VAR intervened after replays showed that the ball had struck Makhanya’s hand during the move before he finished.
The goal was therefore ruled out.
Celtic winger Sebastian Tounekti was booked for dissent immediately afterwards, with the forward making his feelings about the decision known.
That ensured the controversy continued to dominate the contest.
Rangers, though, remained in front.
And as the minutes disappeared, Celtic struggled to find the response they desperately needed after last week’s 3-0 defeat and Thursday night’s 3-1 Europa League loss to Ferencvaros.
McInnes gets another Old Firm victory
Ultimately, Naderi’s first-half goal proved enough.
Rangers held on to secure a 1-0 victory at Celtic Park and complete back-to-back Old Firm victories in the space of seven days.
The result gives McInnes another significant win over Celtic after his side’s emphatic League Cup success at Ibrox.
It also means Rangers have now won both meetings between the sides this season, while Celtic are left to reflect on an extraordinarily difficult week.
For McInnes, however, the afternoon was about far more than the result.
There was the early touchline confrontation with Fotheringham, the controversy surrounding Fernandez’s booking, the VAR intervention to rule out Makhanya’s goal and, ultimately, another Rangers victory over their fiercest rivals.
The manager wanted intensity from his players before kick-off.
He certainly got it from the touchline.