If ever a stadium can be rocked by silence, this was the moment. With no visiting fans allowed at any of this season's Glasgow derbies, Ryan Naderi's winning goal was met with nothing but the banging of fists of the clear plastic of the Rangers bench, and the shouting of the broadcast commentators. A screaming void of apathy and atrophy, the sound of a beckoning abyss, of a title race blowing open and a team slowly breaking apart.

That Rangers were unable to celebrate this triumph with their fans in the stadium was, of course, a source of lament, as well as a measure of just how ugly this fixture has become over the years.

It has become a day that is no longer relished but dreaded, a failure not just of the two fanbases themselves but the authorities who have allowed the ugliness to fester, who have talked a tough game on sectarianism but done little in practice to combat it at source.

But nothing could spoil the mood of Derek McInnes's team, humming after a tough start to the season and now able to toast a second victory over their rivals in the space of a week. For Celtic, sitting on three straight defeats, the silence will be filled with plenty of noises and voices over the coming international break: awkward questions and painful decisions that last season's dramatic double may have forestalled but which can no longer be avoided.

The drop in standards over the opening weeks of this season has been alarming, and at 74 years of age Martin O'Neill is wise enough and self-aware enough to know that he may be as much part of the problem as part of the solution. For him, the next few weeks will be a time of "self-reflection" on his role and his future, on whether he truly has the energy in him for one last fight.

"It's a matter of whether I can help the team, and I'll have a look at that this week," he said. "Every time things don't go so well, age plays a part, and you know what, they may be right. I'm 110 in two years' time. That may be time to wrap it up. But I'll see how it goes.

"Let me generalise a little bit. I got an opportunity to come back last October which I never thought would happen in my life. Winning the league, the game against Hearts, was one of the great moments of my managerial time. But even then, I was still thinking about whether you can still have the energy, the desire. There's nothing great about getting old, I'll tell you that."

What is true of O'Neill may also be true of a few of his players. Is Callum McGregor, club legend but now 33 years of age and increasingly off the pace, still fit for purpose? Does Liam Scales need replacing? Does Kieran Tierney still have the legs? What exactly is James Forrest still doing about the place? And in the meantime, would you remotely trust the Celtic board – still essentially hollow of footballing expertise – to oversee the required transition?

Not on this evidence. The summer signings – Kasper Høgh, Mika Baur, Camilo Durán – largely disappeared from view.

There was fury here but precious little focus, plenty of passion but no real patterns of play, no order to the chaos, no real idea of how to keep the ball or fashion a chance. Rangers dominated the central areas, where Dan Neil and Nicolas Raskin are already forging a formidable partnership and James Penrice merrily stomped all over the place.

O'Neill gambled on a back five, on Luke McCowan in a sort of withdrawn winger role, discarded both at half-time, rolled through his substitutions, but the plan never really emerged from the fog. Celtic are basically like the tangled ball of printer cables and headphone wires in the bottom drawer, where you're never quite sure whether you're unpicking the knots or making them tighter.

Naderi's goal, bundled in from close range after Kim Min-su's long-range effort was parried helpfully into his path by Viljami Sinisalo, was simply the most consequential emblem of Rangers' superiority here. Emmanuel Fernandez got a rough ride early on, Tierney clipped the bar from distance and Ivor Pandur made a fine save from Colby Donovan early in the second half. That was basically it, as far as explicit threat went. Donovan's header was the only Celtic shot on target.

"For a young team, it's brilliant that they can take the good from this," said McInnes. "Coming to places like this, it won't get much more difficult. It's only three points, but in the context of the season it was important for lots of reasons." He knows, of course, that Rangers are not the finished article. But right now there is a power vacuum at the top of Scottish football and his improving side may as well be the one to fill it.