Manchester City's shocking decline and fall was confirmed by their own travelling supporters suffering on the top tier of the Bernabeu as they were being ruthlessly put to the sword by Real Madrid.

The giant clock inside this magnificent arena was on 80 minutes when Mateo Kovacic lined up a tame shot that flew straight at Real keeper Thibaut Courtois, who was probably grateful for the exercise.

City were trailing 3-0, a scoreline that flattered them, so the hardy band of followers decided irony was the best medicine for the torture of watching their once all-conquering side, breaking out into rapturous cheering and applause.

Moments later, with City achieving the rare feat of stringing several passes together, chants of "Ole" came from the travelling support.

This summed up a pitiful, desperate night for manager Pep Guardiola, as they subsided in the most timid fashion, a sense of inevitability draped over the Bernabeu from the moment Kylian Mbappe scored the first goal of a brilliant hat-trick after only four minutes.

Losing to Real Madrid is an occupational hazard of the Champions League. Losing to Real Madrid by barely laying a glove on them is a sign of Manchester City's steep downward curve this season.

The credits were rolling, and not just on their Champions League campaign, as they failed to reach the last 16 for the first time since they failed to get past the group stage in 2012-13.

They are surely rolling, too, on a great team in need of major renovation.

In the most palatial surroundings of this rebuilt stadium, this had the look and feel of the end of an era.

Guardiola almost seemed to accept this was the case as he stated in the aftermath: "Nothing is eternal."

He said: "The best team won. They deserved it. This is the benchmark. We have to accept it and move forward.

"In previous seasons when we were better, it hurt more. We have to accept it and the reality of our team."

Asked whether a rebuild is needed, he said: "We have time. We have 13 games left in the Premier League to get into this competition next season."

City's need for a changing of the guard was made to look even more stark by the ease in which they were dismissed by Real Madrid, yes the holders and the superpower of the Champions League, but also a side they have consistently pushed in matches almost too close to call over several years.

Not here. This was a rout with a casual air.

Real Madrid were able to play within themselves after four minutes, Mbappe's hat-trick completed with superb speed of thought and foot for his second after 33 minutes then a low drive just after the hour.

The Bernabeu, surrounded by thousands of fans forming a welcoming committee for Carlo Ancelotti's side two hours before kick-off, with flares lighting up the Spanish sky and the the smell of cordite in the air, witnessed a procession, a very painful procession for those who travelled from Manchester.

Guardiola, justifiably, will claim mitigating circumstances as Erling Haaland was only fit enough for the bench, not even taking part in the pre-match warm-up after sustaining a knee injury late in the 4-0 win against Newcastle United.

And moments after Mbappe opened the scoring, John Stones suffered another injury and limped off.

It was not that City lost, most observers expected this outcome after the 3-2 defeat in the first leg at Etihad Stadium, it was the manner of the defeat.

City never looked like they believed they could pull off the "perfect" performance Guardiola stated was required to overturn that deficit. This was about as far from perfection as it gets.

And the clues were everywhere that if it is not exactly back to the drawing board for Guardiola after six Premier Leagues, a Champions League, two FA Cups, four League Cups, a Super Cup and a Club World Cup in a magnificent run of successes, then it is certainly time for a new set of plans.

Kevin de Bruyne, who has decorated this fixture over many years, was only on the bench after an ineffectual performance in the first leg.

Stones, 31 in May, is still a pivotal figure but suffers so many injuries, while 34-year-old surprise starter Ilkay Gundogan delivered more evidence that he left his best at Manchester City in his glorious first spell.

Goalkeeper Ederson, 31, is not the guarantee of reliability he once was while gifted midfield metronome Bernardo Silva is not the influence of old as he reaches 30. Jack Grealish, 30 in September, was also only on the bench.

The renewal has started with new faces such as striker Omar Marmoush, who had no service worthy of the name here, and midfielder Nico Gonzalez, as well as 20-year-old defender Abdukodir Khusanov, who suffered as he was pressed into service in an unaccustomed right-back role.

It was a tough night for the young defender, clearly seen as a weakness in City's make-up and relentlessly targeted down the flank.

Guardiola's takeaway from this harrowing night must be that he needs a ruthless cull of those older names, players who have delivered so magnificently for him.

Rarely has such an elite team's form and quality fallen off the cliff so fast and so hard.

This is a team that has been allowed to grow too old together, that is now unable to find the old hunger that enabled it to return to the well of success so brilliantly year after year.

Guardiola has signed a new two-year contract and his task must be to fashion a new team before it is time to discuss another deal.

The Bernabeu is the most unforgiving arena in the Champions League, its stunning refurbishment complete with five tiers of stands looking down on City's demise.

It was a particular galling night for Guardiola, not simply because the task in front of him was laid out in graphic, gruesome detail before his very eyes, but also because Real Madrid's fans revelled in his discomfort as a result of his Barcelona allegiances.

Guardiola's name was met with deafening jeers and whistles when it was read out before kick-off, and when one of the many giant screens captured his despair in close-up after Mbappe's early strike, a huge roar of delight swept around the stadium.

As City players trooped disconsolately away at the final whistle, some of them perhaps on their way out of this tournament forever with this club, there was no consolation to be had, certainly not from Gonzalez's late goal.

Manchester City have had a magnificent run. They have lit up domestic and European competition with the quality of their football but this was a night when it looked like their race was run. It is time for change.

The dismissive way they were treated by a Real Madrid side they have regarded as rivals in recent years showed they need new blood to return to that former golden status.

It happens to the best of them and Manchester City were the best of them. Not any more.