Guardiola was concerned his treble-chasing side may suffer a hangover in Sussex following the jubilation of the weekend’s title celebrations.
But the Spaniard was pleasantly surprised by the performance of his players during a gripping south-coast contest.
Phil Foden fired City ahead at the Amex Stadium before Julio Enciso’s stunning equaliser cemented sixth-placed Albion’s place in next season’s Europa League.
“I was a little bit worried about how much we would drop our (level) with what we had done the last four, five, six months,” said Guardiola.
“Forty hours (ago) we drank all the alcohol in Manchester and the way they played was outstanding.
“I enjoyed it a lot, especially being champions.
“You have to come here to win the game, we know it will be tough. They are a fantastic team in all departments, that’s why they are in the Europa League, well deserved.
“And also we showed why we are the best team in England.”
Guardiola had a relatively early night after the trophy presentation which followed Sunday’s 1-0 win over Chelsea, while City’s players recovered with saunas the next day.
“At 10.30pm, I was in bed with my wife, I was exhausted,” he said.
“I watched Match of the Day and I slept like a baby but I know the players did what they have to do.
“When you win the Premier League you have to celebrate. They did it with the families, they enjoyed it a lot and the next morning was just sauna time.
“And the day after, we talked a little bit in the afternoon: ‘Guys, we have to be ready for Brighton’ and they did it.”
City, who complete a victorious top-flight campaign at Brentford on Sunday, were given a guard of honour by their hosts ahead of kick-off.
Foden opened the scoring in the 25th minute with his fifth goal in as many starts against the Seagulls before Enciso’s spectacular finish halted City’s top-flight winning streak at 12 games.
Guardiola believes the high-level contest will be vital preparation for the forthcoming FA Cup final against Manchester United, which is followed by a Champions League showdown with Inter Milan in Istanbul.
“We need these opponents to bring us in our maximum,” he said. “This is so important. Brentford will be the same.
“It’s really, really good the teams help us maintain that level because the finals you have to play in that level otherwise it will be so difficult.”
Guardiola was hopeful regarding the knocks which forced off Foden and John Stones, while confirming the absentees – Nathan Ake, Ruben Dias, Aymeric Laporte, Manuel Akanji and Jack Grealish – have injury issues.
The thrilling encounter was a fitting final home game of an unforgettable campaign for record-breaking Brighton and banished the remote chance of them slipping into the Europa Conference League on the final day at seventh-placed Aston Villa.
Tonight's dressing room SCENES! 😍 pic.twitter.com/tGsyvE7Wyl
— Brighton & Hove Albion (@OfficialBHAFC) May 24, 2023
Seagulls head coach Roberto De Zerbi said: “I am happy because we have to respect our club, our fans but we have to show the courage, show we believe in ourselves to win against the best team in the world.
“We needed one point. We didn’t receive a gift. We deserved to make a point today.
“I am really proud because I think today has been one of the best games in this season.
“(It was) very tough but we played with an incredible quality. We deserve to play in the Europa League for our mentality.”