Guardiola’s best teams have been built on control, patterns of play and attacking incision.
When City beat Wolves 4-0 on the opening weekend of the season, it was natural to think the troubles that had plagued them last term had been erased over the summer.
But Sunday’s defeat on the south coast was a repeat of the inconsistency City displayed throughout last season.
Guardiola’s side stifled Brighton in the first half, limiting the Seagulls to a single opportunity through Kaoru Mitoma.
Haaland, making his 100th Premier League appearance for City, opened the scoring with his 88th league goal for the club.
But a quadruple substitution by Brighton boss Fabian Hurzeler after an hour changed the course of the game, with James Milner, Brajan Gruda, Georginio Rutter and Yasin Ayari entering the fray.
Brighton dominated from there on, equalising from the penalty spot through Milner, before a last-minute winner from Gruda.
“We conceded two goals. We were excellent for one hour,” Guardiola told Sport.
“After the goal we forgot to play. We were thinking of the consequences.
“I like many, many things we are doing. Like against Tottenham, we started well. I like many things the team has done here today but we were unable to win. When we conceded the goal, we stopped playing.
“It’s one game. The season has just started. There is a long, long season ahead of us. We will see what happens.”
Only Manchester United’s 1992-1993 title-winning team have recovered from losing two of their first three league matches to be crowned champions, and that came during a 42-game season.
“It’s back to the drawing board for Man City,” said former Chelsea and Middlesbrough goalkeeper Mark Schwarzer.
“There are a lot of questions still about this team and Pep Guardiola. Is he going to turn it around? He has never been in a situation quite like this before and the hole keeps getting deeper and deeper.”