Spurs survived a seven-goal thriller on Wednesday night at the Etihad, losing the battle 4-3 but winning the war on away goals thanks to their 1-0 victory in the first leg a titanic quarter-final tie.
A match that saw City lead 1-0, trail 2-1, then forge ahead 4-2 to lead the tie for the first time before Fernando Llorente's controversial decisive goal was allowed to stand after a VAR check for handball, brought one final twist in stoppage time.
Guardiola scampered down the touchline in celebration when Raheem Sterling thought he had completed his hat-trick with the goal to take City into the semi-finals for just the second time.
Seconds later, delirium turned to disbelief, as Guardiola sank to his knees in the realisation that VAR had revealed an offside earlier in the move.
Guardiola described the exit as "cruel."
Winning the Champions League remains the grail for the club's Abu Dhabi owners after a decade of pouring money into the club, but no one can say they were not entertained.
For the much-lauded Catalan coach, though, the elimination continues a pattern of Champions League anguish since he won the title for a second time with his great Barcelona team in 2011.
Guardiola's Barca reign ended in semi-final defeat to Chelsea in 2012 and there were last four exits in each of his three seasons at Bayern Munich.
The upturn in City's standards since he arrived in 2016 is unquestionable, and they could still complete an unprecedented treble of Premier League, FA Cup and League Cup in England.
However, it is for Champions League success that Guardiola was pursued so long by City, and in three attempts he has failed to even reach the semi-finals.
Guardiola has consistently played down City's potential as a European powerhouse in his three years in charge, contrasting their lack of historic success to Barca, Bayern and Real Madrid.
But it is Monaco, Liverpool and now a Spurs side 16 points adrift of City in the Premier League, that have sent his expensively assembled squad packing in the Champions League.
A common theme has been City's poor defensive record. Monaco scored three times in both legs in the last 16 in 2017, Liverpool thrice in 31 minutes to take a decisive lead in last season's quarter-final and, even shorn of Harry Kane, Tottenham became just the second visiting side this season to score three at the Etihad.
Guardiola will contend that is why his approach for the first leg was more conservative, but the lack of an away goal ultimately cost him.
The decision to leave out Kevin de Bruyne in north London last week was even more questionable after the Belgian bagged a hat-trick of brilliant assists on Wednesday.
"Guardiola might say that the passages of chaos here, as City traded goals with Spurs like an under-nines match after too many Haribos, explained why he had tightened up at the Tottenham Hotspur Stadium with Fernandinho alongside Ilkay Gundogan, showing untypical caution," wrote The Times.
"But others, even David Silva, could have made way. You wonder if there can ever be a right time to omit a fit De Bruyne when you marvelled at his hat-trick of assists here."
A Premier League title is still to be won for City and there is little time to reflect before Tottenham visit again on Saturday.
Winning their last five league games would deliver an eighth league title in 10 seasons across three countries for Guardiola.
But after seven straight failed attempts, questions remain over his suitability for the cut-throat nature of the Champions League.
"There is a theory that Guardiola, the master of control and systems, just isn't suited to the intangibles of one-off knockout football," wrote The Guardian.
"Nights where an entire campaign can be thrown away in a fit of human frailty or a surge of irresistible emotion."