Sergio Aguero netted a 69th-minute equaliser in a gripping 1-1 draw with Liverpool on Sunday to prevent Manchester City losing ground in the battle for a top-four Premier League finish.
Liverpool looked poised to leapfrog City into third place after James Milner silenced the boos from fans of his former club to give the visitors the lead with a penalty early in the second half.
But Aguero's strike kept City a point above their rivals, who have played a game more, and provided a moment of solace after their mid-week Champions League elimination at Monaco's hands.
"After the Champions League, the last few days at training people were so, so, sad. People don't talk too much," Guardiola told Sky Sports.
"We arrive here against Liverpool, who have no Europe all season and one week to prepare. The spirit, how we played, it is one of my happiest days as a manager."
Guardiola had come in for criticism after City's 3-1 loss at Stade Louis II, but his side will approach back-to-back trips to Arsenal and Chelsea on the back of a seven-game unbeaten run in the league.
While Jurgen Klopp failed to become the first manager to do a league double over Guardiola, his Liverpool team are now unbeaten in 10 games against their fellow top-six sides this season.
"To get a point at Manchester City for each team in the world is absolutely OK," said the Liverpool manager.
"They deserved the goal, but we could have scored more. Two highly motivated sides, both wanted to win until the last seconds."
A rain-slicked pitch and two attack-minded teams made for a furious first half at the Etihad Stadium, characterised by City possession and Liverpool counter-attacks.
City unambiguously targeted the flanks, Leroy Sane on the left and ex-Liverpool man Raheem Sterling on the right whipping a succession of low, pacy crosses across Simon Mignolet's six-yard box.
Twice, Aguero felt he had been unfairly impeded as he tried to get on the end of them, first by Joel Matip and then Ragnar Klavan.
- Lallana misses kick -
The latter incident, in the 43rd minute, also saw Sterling taken out by a despairing Milner as the pair stretched for David Silva's low cross, with Fernandinho sliding the ball wide at the back post.
City's clearest opening of the half saw Silva thrash the ball inches wide of the left-hand post after Mignolet had jutted out his left foot to fend off a drive from Sane.
But the best chances of the first period were all Liverpool's.
An under-hit John Stones back-pass let in Sadio Mane, only for an authoritative sortie by goalkeeper Willy Caballero, allied to a subtle tug from Nicolas Otamendi, to save the day.
Philippe Coutinho bent a shot just over, Matip headed wide at a free-kick and Caballero showed agility to claw away a Roberto Firmino curler and touch over a thumping Adam Lallana volley.
After Mane had seen a shot blocked by Stones, Liverpool went ahead in the sixth minute of the second half.
Gael Clichy was penalised for a high, untidy challenge on Firmino as the Brazilian chested down Emre Can's flighted pass and Milner swept the penalty into the bottom-left corner.
Firmino looked poised to double the visitors' lead from Coutinho's measured through ball, but Caballero stood up well to save.
Eight minutes later it was all square as Kevin De Bruyne's brilliantly measured cross from the right was unerringly dispatched by Aguero.
Aguero looked set to put City ahead in the 76th minute, but after a neat one-two with Sane he stumbled, De Bruyne scuffing the loose ball against the post.
An increasingly end-to-end contest then spat out a glorious chance for Lallana, but from Firmino's knock-down and with Mignolet's goal at his mercy, he missed his kick.
As the noise levels rose, Sterling and Aguero -- twice -- spurned late chances, but a draw felt an appropriate outcome.