When Martin O’Neill voiced concerns this week regarding Celtic’s need to adapt to the evolving landscape of Scottish football, he was addressing an audience already in agreement. His assertion highlighted the club’s lack of preparation for heightened competition this season, reinforcing the necessity for some deep reflection as the season draws to a close.

However, one aspect at Parkhead might not require a shake-up. The decision to part ways with O’Neill to make room for Wilfred Nancy last year was a misstep by the club’s leadership. Overlooking the opportunity to invite O’Neill back for another year would be yet another blunder.

Since taking the helm, O’Neill has steered Celtic through 18 domestic matches, achieving 15 victories, two draws, and suffering only a single defeat. His knack for pulling off results against the odds was once again evident, showcasing his adept leadership.

This season, Celtic has often been less than impressive in attack, yet they continue to eke out victories. These successes are largely due to an extraordinary defensive effort and an indomitable spirit.

His ability to dig out results against the odds was underscored here and then some.

Celtic’s players take off to celebrate after Cvancara scores the decisive shootout penalty

Not for the first time this season, Celtic were seriously underwhelming on the front foot. Yet again, they scraped through. It owed everything to a phenomenal rearguard action and an iron will.

O’Neill’s ability to prevail when all logic suggests his team should not is – to coin one of his favourite words – remarkable.

This, though, was taking matters to extreme. By the end of extra-time, the statistics showed Celtic hadn’t managed a single shot on target.

They got there through four expertly-taken penalties, while Rangers twice erred from 12 yards. Somehow, they limped into the last four of the Scottish Cup.

This was another painful day for Danny Rohl. Across the past couple of weeks, the Rangers head coach hasn’t half made a lot of noise.

All those unwarranted remarks pertaining to O’Neill’s team selection and strategy in Stuttgart. His spurious claim that Dujon Sterling’s handball last Sunday may not have constituted a penalty. The demand that his players screwed down the volume on 7,500 Celtic fans here.

Amid the bluff and bluster, though, he did hit one nail firmly on the head. That the need for anyone in his position to win silverware is non-negotiable.

Both domestic cups are now gone, as is Europe, while his team are trailing Hearts by six points in the league. From a position of promise, the German is now a man under serious scrutiny. His side’s mentality is being widely questioned.

The fact Rohl’s men played most of the football in what was truthfully a poor match will be no consolation to those of a light blue persuasion who watched it. If a team don’t score in open play, they can’t claim to have been part of a hard-luck story.

For the Celtic fans congregating in the visiting end for the first time since 2018, the team news was not what they were looking for.

While Kieran Tierney’s absence after picking up a knock at Pittodrie wasn’t entirely unforeseen, skipper Callum McGregor’s was.

There were a couple of curveballs for Rangers fans to digest, too, with John Souttar and Tochi Chukwuani dropped.

Celtic boss Martin O’Neill inspired his team to dig deep in their quarter-final win at Ibrox 

O’Neill wouldn’t have needed McGregor to be on the sidelines for his importance to be made apparent, but the opening 30 minutes underscored the point.

Although Luke McCowan did his utmost to compete in the holding role, Celtic lacked that first pass and an individual to set the tempo. Rangers thrived on it.

Slackness by McCowan served up an early opening for Youssef Chermiti. Last week’s two-goal hero fired wildly over the top. It was to be the story of his day.

Mohamed Diomande had been the beneficiary of Chukwuani dropping to the bench. He spent the first half walking a tightrope, however, with an ill-advised scything of Julian Araujo which put him on a yellow card inside two minutes. Unsurprisingly, he didn’t reappear for the second period.

Rohl was convinced his side should have had an early penalty when Chermiti’s shot struck Auston Trusty on the hand, but the American’s arm was tucked in.

Rangers were well on top in the early exchanges. Playing with energy and aggression, there was an edge to their play which Celtic just didn’t have.

O’Neill’s men lacked someone putting their foot on the ball. They made elementary errors and were crowded out on the rare occasions they crossed the half-way line.

On the flanks, Yang Hyun-Jun and Sebastian Tounekti were bystanders. Deployed as a centre forward, Daizen Maeda chased everything down but was starved of meaningful service.

The visitors’ efforts in the opening spell were best summed up by Araujo putting a throw-in straight out of play.

Trusty had to be alert to eat up the turf and get a foot in when Ryan Naderi threatened to gather a percentage ball over the top.

Celtic did belatedly find something. Ten minutes from the break, they had the ball in the net, yet to no avail.

Having had his initial corner blocked, McCowan delivered at the second attempt. Scales flicked it on. Maeda’s diving header crept in at the far post only for a VAR review to show Scales was offside.

Rohl will still have been miffed that his side hadn’t established a lead. Sterling did his best to provide it when he dispossessed Tounekti and advanced down the right. His cross was met by Chermiti. Again, the forward only found the stand.

Celtic defender Benjamin Arthur hadn’t put a foot wrong until he let a back-pass roll under his foot early in the second period. Chermiti looked set to capitalise. Viljami Sinisalo had to be smartly off his line.

Rangers boss Danny Rohl and winger Mikey Moore see their team lose the penalty shootout 

With Rangers’ pressure mounting again, Trusty slid in to send Mikey Moore’s shot over the top.

From a Moore corner, a scramble ensued which forced Tounekti to hack Chermiti’s flick off the line.

Seeking to change the flow, O’Neill threw on a raft of substitutes around the hour mark, including Alex Oxlade-Chamberlain.

Rangers still fired in cross after cross. Sinisalo’s handling and command of his box were first-rate.

In what was to be his last action of day, Moore slashed a half chance over from Chermiti’s knock-down.

From a corner, Nico Raskin forced Benjamin Nygren to clear the ball off the line. We were going the distance.

Rangers continued to press. Chermiti was thwarted by a superb block by substitute Dane Murray.

Manny Fernandez succeeded in bundling home James Tavernier’s corner, only for VAR to spot that he had clearly used his arm.

Tavernier’s fresh legs from the bench set up another chance for Chermiti. This time his shot flashed a foot wide of the upright.

Things got increasingly frantic. Also introduced, Souttar was grateful to Butland for beating Tomas Cvancara to a loose ball after he hesitated. There was just no separating the teams over 120 minutes.

With the spot-kicks taken at the home end, Tavernier clipped the bar with his side’s first before Djeidi Gassama sent the fourth skywards.

By then, Oxlade-Chamberlain, Auston Trusty and Hatate had found the net.

It cleared the stage for Cvancara to send Butland the wrong way and send Celtic into the semi-final, albeit the disgraceful scenes on the pitch involving both sets of fans would overshadow all that had gone before.