Celtic were given an almighty fright by Championship leaders Falkirk before a Nicolas Kuhn inspired fightback and a quickfire Adam Idah double turned this League Cup tie on its head for Brendan Rodgers’ side, who eventually booked their place in the semi-finals of the competition with a bit to spare.

John McGlynn’s team had twice led at Celtic Park, and were good value for it too, troubling the hosts with their high pressing, relentless energy and physicality.

Celtic, by contrast, looked disjointed for the first hour of the contest. Manager Rodgers had made eight changes to his team from the thumping win over Slovan Bratislava in midweek, and too many of his fringe men failed to hit the standard expected.

It was a fine strike from Ross MacIver that had Falkirk ahead early on, before a crashing Paulo Bernardo volley looked to have settled Celtic down. The Bairns hit back though to stun Celtic Park once more, as an expertly guided header from Finn Yeats had them ahead at the interval.

A raft of substitutions on the hour though turned the tide, with Kuhn proving just too hot for a tiring Falkirk defence to handle. He set up Idah for both of his goals to put Celtic ahead, before he got in on the act himself with a double of his own to put the icing on the cake of a brilliant cameo performance from the winger.

Falkirk substitute Michael McKenna was given a straight red for a challenge on Anthony Ralston at the death, with it all rather falling flat for the brave visitors in the end.

Here are the talking points from Celtic Park…

Kuhn leads the cavalry to dig sloppy Celts out of a hole

It was always going to be a tough ask for Falkirk to win at Celtic Park no matter what, but it also helped the hosts that they had several multi-million-pound signings to throw on when they were in a spot of bother.

So it was when an hour into the game, Rodgers had seen enough, putting struggling debutant Alex Valle out of his misery and removing the ineffective Luis Palma along with James Forrest and Reo Hatate, and sending on £11m man Engels, Kuhn, Hyun-jun Yang and Greg Taylor.

The truth is, there was no one among the fringe men who really did themselves justice for Celtic, and Rodgers will have wanted to avoid having to send for his heavy hitters. He had no choice though, with Celtic staring down the barrel of an almighty cup shock.

Yang got the first shot away that had troubled Nicky Hogarth in an age, and after winning a couple of corners, a flurry of Celtic pressure paid off. Ralston played a nice pass through to Kuhn, who got to the byline and cut it across for Idah to tap home into an empty net to drag Celtic level.

Straight from the kick off, Kuhn was at it again, winning the ball from Sean Mackie in Falkirk’s left back position and playing in Idah, who bundled his way through the Falkirk backline to get his second in quick succession and leave the visiting players devastated.

Kuhn wasn’t finished there though, and he finally made sure of Celtic’s safe passage as he latched onto an Engels through ball and drew Hogarth before clipping the ball over him and into the net, and then pounced on a loose ball to thump home the fifth.

Falkirk shock troops share the plaudits

It was little wonder that the huge Falkirk travelling support stayed behind to hail their heroes, who gave Celtic perhaps the best game they have had here in a long, long time.

One thing that was certain was that under John McGlynn, they would come to the home of the Scottish champions and play the same way they do when they’re up against Queen’s Park or Hamilton at home.

They were going to have a go alright, and they shook Celtic not once, but twice, to have nerves jangling all around the stadium.

The opener came as a hopeful cross to the back post was contested by Falkirk attacker Alfredo Agyeman – outstanding on the day - and Valle, and it broke towards MacIver at the edge of the area. Valle complained that he was being held as he tried to get out to block, but MacIver wasn’t hanging around for the referee blowing his whistle.

Instead, he stepped onto the loose ball and fired an arrow of a low effort past Kasper Schmeichel’s left-hand post from the edge of the area, a stunning effort, in more ways than one.

Celtic fail to build on Bernardo peach

The Celtic response to that gut-punch wasn’t immediate, but it was emphatic.

Hatate chipped the ball in from the left, and it was headed on by Valle into the centre of the box.

Arriving there was Bernardo, who - perhaps taking out all of his frustration at missing out on a start against Slovan Bratislava during the week – crashed the ball beyond Hogarth on the volley to bring Celtic level.

The vast majority of those inside Celtic Park may have sat back and expected their team to go on and steamroller their Championship opposition from there, but McGlynn’s upstarts had other ideas…

Unhappy Valle exposed again

Incredibly, Falkirk took the lead once more just before the break, and again, Valle’s lack of physicality was exposed, as Agyeman shrugged him off before getting his head up and clipping a perfect cross to the back stick, where Falkirk had a man over.

Yeats coming into the side was the only change that McGlynn made to his line up from the win over Airdrieonians last time out, and the decision paid off handsomely for the Falkirk manager as he was the man who timed his run perfectly to guide a header expertly into the bottom corner.

It is early days for the on loan Barcelona youngster, of course, but perhaps the value of Taylor was laid bare by his absence here.

Rusty Auston Trusty has job on his hands to get into side

As with Valle, it is far too early of course to be making snap judgements about Trusty, but the £5m centre back would have wanted to show the Celtic fans and his manager what he was capable of here given the task he has in breaking up the partnership between Liam Scales and Cameron Carter-Vickers.

He didn’t really give those two much to worry about though, with his distribution often wayward and his partnership with Stephen Welsh inspiring little else other than the heebie jeebies in the stands.