Why evergreen Forrest is Celtic's enduring influencer

St Mirren did their darndest to change the storyline. Everything is degrees of sweatiness for Celtic these days and this was another deeply uncomfortable afternoon before the floodgates were forced open and St Mirren washed away.

At the break, when leading 2-0, it looked like a rare thing of late was going to happen - a Celtic stroll. They'd taken the lead when St Mirren goalkeeper Ryan Mullen delayed a clearance and was suckered by Daizen Maeda sneaking up on his blindside like a lion sizing up an unsuspecting antelope. The outcome could not have been uglier for St Mirren or prettier for Maeda.

He got them off to a flyer and Celtic looked sharp. They hit the woodwork twice, they had a danger about them for a little while. St Mirren lost Mullen to injury and had to replace him with the only fit option, 17-year-old Grant Tamosevicius, playing in his first senior game. No pressure, son.

St Mirren found plenty in adversity. Tempo, aggression, work-rate. They pushed Celtic back, hustled them and harried them, lived in their face and watched them struggle.

Mikael Mandron made it 2-1 then 2-2 and they deserved it. Celtic were like a boxer on the ropes, ahead on points and hoping to see out the final moments by covering up as best they could. They got caught. Into extra time it went. And into orbit went Forrest's impact.

Lennon was there to see it. Dunfermline will be underdogs in the final but given that his own team have already beaten Hibs, Aberdeen and Falkirk on their way back to Hampden and haven't conceded a goal to any of them, then he can't have witnessed too much to scare him.

The goal-fest was Celtic at their most ruthless but it was unlike them this season. If they could deliver that kind of efficiency and class in front of goal for the reminder of the season then it's conceivable they would motor on to a double.

There'll be huge encouragement in Iheanacho's performance, a dangerous weapon and the best tool Celtic have for the run-in. His two goals were timely, to put it mildly. Winger Maeda, for all his phenomenal work-rate, is not the centre-forward Celtic need right now.

O'Neill has many things to ponder. What an end game awaits. Five league games and one cup final, the last act against one of his greatest leaders of the past.

They shared a television gantry at the end. Laughing and joking, the mood will be a little more intense the next time they meet.