In amongst the mayhem that broke out shortly after full-time, Danny Rohl walked around the centre circle, shaking his head whilst trying to console his players.

What could he possibly say to them after this 2-2 draw? What crumbs of comfort could he find that would make this meek surrender any more palatable?

From a position of supreme command as they led 2-0 at half-time, Rangers bottled it good and proper over the course of a woeful second half.

They had their heels pressed firmly on Celtic’s throats at the interval, only for the great green revival to blow them off course from what would have been a huge three points.

This collapse is on Rohl. He has earned a lot of praise and plaudits over recent months, but his team collapsed in the second half here against a resurgent Celtic.

In the derby away at Parkhead at the turn of the year, Rohl made a couple of changes at half-time that turned a 1-0 deficit into a 3-1 win.

Rangers boss Danny Rohl could not stem the flow as Celtic roared back in the second half 

Reo Hatate scores a late equaliser for Celtic after his penalty was saved by Jack Butland

Celtic boss Martin O’Neill tries to calm the players down as tempers become frayed at full-time

This was effectively the mirror image of that. It was Martin O’Neill who made the changes at half-time – and his team looked transformed.

During that onslaught in the first half, Celtic looked like a team whose season was on the verge of imploding.

They were awful. Rangers were utterly dominant and perhaps should have been more than just two goals ahead.

Those words from Luke McCowan in Stuttgart on Thursday night, when he claimed that no team in Scotland can touch Celtic, looked very silly indeed.

But, in the fullness of time, this might just prove to be 45 minutes where O’Neill and Celtic saved their season.

Rohl had no answers. His changes did not work. Seeking to stem the flow after Kieran Tierney pulled a goal back shortly after the break, he cut an animated figure on the touchline.

Like a man who could see a train coming down the tracks but couldn’t free himself in time to avoid it.

When Reo Hatate scored the equaliser with only a couple of minutes to play, it capped what had been a train-wreck of a second half for Rangers.

This is a major blot on Rohl’s copybook. His team had a chance to gain some vital ground in the title race but blew it.

The real winners of this match were at the other end of the M8. No longer heading off to Dubai for a training camp, this was a brilliant day for Hearts.

For Celtic and O’Neill, the pulse is still there but only just. He will know that his team simply cannot start as poorly as this and hope to get away with it much more.

The extent of Celtic’s problems this season run far deeper than a lack of strong and competent centre-halves, but the ineptitude of their own decision-making has only made the issue worse.

Turn the clock back to late October and the 3-1 defeat to Hearts, a match which proved to be Brendan Rodgers’ last in charge before resigning.

It was glaringly obvious back then that Dane Murray’s limitations will be exposed in these high-octane, high-pressure affairs.

He had a nightmare that day at Tynecastle and didn’t fare much better here at Ibrox. Watching him thrash around, slicing clearances and looking hopelessly out of his depth, it was painful.

Meanwhile, Benjamin Arthur, the 20-year-old signed on loan from Brentford in January with barely any experience in senior football, was on the bench.

Not only would Stephen Welsh start for this Celtic team, he would actually be the best centre-back at the club in the absence of Cameron Carter-Vickers.

But Celtic chose to send him back on loan to Motherwell. On every conceivable level, it was a decision which made no sense whatsoever.

Murray was part of a Celtic defence whose heads must have been spinning after the Rangers assault over the opening half-hour.

On his 74th birthday, O’Neill’s side were all over the shop. Going with a 4-3-3 against Rangers’ 4-2-2-2 system, Celtic had an extra body in midfield, but you would never have known.

It was no surprise that O’Neill chose to make a couple of changes at half-time — and, credit where it’s due, his team looked all the better for it.

The intensity of Celtic’s pressing was so much more aggressive. Meeting Rangers 10 yards higher up the pitch, they soon had the home crowd spooked when a Kieran Tierney header made it 2-1.

It was incredible how the whole momentum of the match shifted. It was almost a mirror image of the game at Parkhead at the turn of the year, when Rohl’s half-time changes sparked a comeback.

It does not do it justice to describe this as a missed opportunity for Rangers. In that second half, they were a team who totally lost their nerve.

They fought back to claim a 2-2 draw at Livingston last week. The boot was on the other foot here at Ibrox.

But these have been two results over the past week which may well have caused irreparable damage to their title challenge.