"I think they drank a lot of beers in the last week,'' Guardiola said, "but they arrived here with no beers in their blood, which is why I give us a lot of credit."
A merciless attacking display sparked by City scorers Kevin De Bruyne, Raheem Sterling and Phil Foden consigned Liverpool to an embarrassing loss exactly a week after their 30-year title drought ended.
The only time Liverpool's players looked like Premier League champions was when they were given a guard of honour from last year's winners, City.
"They were quicker than us in mind -- we lacked fluidity,'' Liverpool manager Jurgen Klopp said. "Isn't it nice another team can be champions when Man City play so well?''
The slack defending and lack of sharpness from Liverpool was perhaps forgivable from players who had spent the previous 31 rounds establishing an unprecedented 23-point lead to become England's earliest champions.
Such an emphatic loss is not how Liverpool wanted to close out such a memorable season. Especially when there are still enough games to overhaul City's record 100-point haul from 2017-18.
Klopp wasn't as downbeat as the result suggested.
"I saw a brilliant attitude, I saw boys who were fighting with all their effort,'' he said. "We didn't behave like somebody who became champions a week ago."
It was a night to forget for so many Liverpool players -- particularly Joe Gomez, who dragged down Sterling to concede a penalty converted by De Bruyne in the 25th minute.
"We tried to play football, taking risks," Guardiola said, "because they are the best team I ever faced in my life with high pressing, it is incredible how fast they are, how quick they play.''
It summed up Liverpool's night that the fourth goal came from an own goal after another blistering City attacking move. De Bruyne picked out Sterling, who turned Andy Robertson and sent in a shot that was diverted into his own net by Alex Oxlade-Chamberlain.
There is still unfinished business for City before the pandemic-delayed conclusion to the season in August. City play Arsenal in the FA Cup semifinals and have a 2-1 lead over Real Madrid after the first leg of the Champions League's interrupted Round of 16.
"This is a team that is evolving and changing -- you can see the maturity Phil is playing with," Sterling said. "I think in the future we have some great players.
"Next season started today and we did well.
"We were disappointed at times this season having lost some games we shouldn't have ... So we had a test against the new champions and [a chance] to make a point.''
The Associated Press contributed to this report.