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 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.
John 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.