It was muggy all right, but it was high pressing rather than high pressure that accounted for Rangers wilting in the heat of battle.

Lightning can strike twice. It did so in the east end of Glasgow as Rangers were reduced to quivering wrecks at the hands of their rivals for the second time inside eight months.

A weatherman or woman isn't necessary to know which way the wind is blowing. It’s looking gloomy for Giovanni van Bronckhorst’s hopes of wrestling the league title from Celtic. Saturday’s performance from Ange Postecoglou’s side seemed to suggest they were only getting into their stride last season. As far as Rangers' domestic ambitions are concerned, it already seems slightly bleak down Govan way.

Ange Postecoglou's team are playing an exceptionally attractive brand of football.

Following the final whistle on Sunday some were wondering whether this was the best Celtic team since, well, when exactly?

Martin O’Neill’s side of the early 2000s are often regarded as the marker in terms of recent times when this discussion is waged.

While Henrik Larsson was at another level, and would augment the current side, O’Neill’s side may well lose out in the pleasing-to-the-eye stakes when compared to Postecoglou’s slick team.

This needs to be acknowledged when attempting an assessment of where Rangers currently are – and where they need to be.

Liel Abada leads the Celtic celebrations at full time after a huge win for the club against Rangers.

Not many teams could live with Celtic at present, although the one scheduled to visit Celtic Park on Tuesday might be better equipped than most to weather the storm.

Postecoglou doesn’t intend to do anything dramatically different against Real Madrid so it will be interesting to see how a genuinely stellar side copes with such intensity.

The entire stadium seemed to be working in cahoots to down Rangers on Saturday. Ball boys and girls recycled the ball at a frightening pace. Celtic took the lead from a quickly taken throw-in at the far side.

Rangers should have been wise to the dangers of switching off since this contributed to their 3-0 defeat in February. Van Bronckhorst even addressed the matter on Friday and sounded confident that his players would not succumb to such lapses in concentration.

The dejected Rangers players trudge off after a galling afternoon in the east end of Glasgow.

Carlo Ancelotti's Real Madrid side won't have such an appetite for self-destruction, but the hosts are nevertheless relishing this opening Group F fixture.

David Turnbull enjoyed a dream cameo at the weekend when he came on to score his first Old Firm derby goal. He won’t have many better opportunities to make his mark in such a high-octane game than being passed the ball by the opposition ‘keeper just minutes after coming on.

Knowing his side were already three goals up meant there was little jeopardy involved. He stroked the ball past the stricken Jon McLaughlin.

“I was just buzzing that it fell to me,” Turnbull reflected afterwards. “I don’t quite know how it happened, it was all in the one movement, but it was great to get the ball and it was then just about keeping calm and putting it away and I did that.”

Celtic v Real Madrid is a fixture that sounds like it belongs in the Champions League. It’s nights like these that Turnbull envisaged experiencing when he joined from Motherwell. He still has Real Madrid strips in a loft at home from birthdays when he was a boy.

“After the game, I think we might look back on it and think it was a great experience,” he said. “Obviously, it’s a great game and you grow up wanting to play in them. But going into it, we’ll treat it as another one and just try to play our football.

“It’s a huge club. They have won the Champions League the most times, I’m sure, so to come up against them will be great.”

Turnbull will be hoping he isn’t forced to admire the likes of Luka Modric and Toni Kroos from the bench tomorrow evening. Although firmly in the twilight of their careers, Modric and Kroos, 36 and 32 respectively, remain supreme practitioners of the midfield art.

“It’ll be great to come across and up against them,” said Turnbull. “I have watched them for years and admired how they play.”

Turnbull is a fully paid-up fan, of the incomparable Modric in particular. He looked on from the sidelines – Turnbull was an unused sub – when Scotland were dumped out of Euro 2020 by Croatia at Hampden, with Modric scoring an exceptional goal in his side's 3-1 win.

“He’s calm on the ball, very technical and has great control and passing,” said Turnbull. “It’s my position as well. It’s just everything about him, I'd say. He's a joy to watch. He was frightening that day. That’s the players you want to play against.”

In view of Postecoglou’s determination to “come out swinging” against Real Madrid, Turnbull, although an unlikely starter, could well be required to contribute at some stage. Playing at Celtic’s intensity makes it impossible for players, particularly midfielders, to last the pace.

Van Bronckhorst’s concerns, meanwhile, are more acute: such as who should he pick between the sticks against Ajax on Wednesday.

He will surely be considering a return for Allan McGregor after Jon McLaughlin endured a Parkhead outing to forget. But the Dutchman will be mindful of the potential consequences for McLaughlin’s Ibrox career if he decides to discard him on the strength of Saturday’s showing alone. That may well be what informs his choice.

As well as McLaughlin, should he play, others at Ibrox will be required to demonstrate their mettle.

Rangers answered their critics by beating Hearts 5-0 in the next game after the alarming 3-0 loss to Celtic earlier this year. They then managed to claim the scalp of Borussia Dortmund shortly afterwards.

The result didn’t derail their season although they were not able to recover in the league. Celtic occupied the summit from that moment on. It’s now incumbent upon Rangers to respond to this latest statement of intent.

Celtic lightning struck Rangers once again - is this the century's best team and will Giovanni van Bronckhorst do what is necessary