Manchester City fell five points behind Liverpool at the top of the table after a shocking 3-2 defeat at promoted Norwich City.
Player of the month Pukki pounced after some abject Manchester City defending and there was no way back for Pep Guardiola's men, despite Rodri's strike three minutes from time giving them hope.
Jurgen Klopp's side won 3-1 over Newcastle earlier in the day, but City could not respond and instead slumped to a damaging defeat, their run of nine away wins in a row over.
"I don't think many people gave us a chance but we came out fighting," McLean said in a postmatch interview. "There were plenty of injuries but we couldn't use that as an excuse. We have a good squad, a good bench and the performance was excellent.
"We got off to a flyer and we knew they would have plenty of the ball. We knew the counter-attack and set pieces would be vital for us and it worked out that way."
The champions met stern resistance from the home side in the opening exchanges, finding it particularly difficult to break a committed Norwich down. And it got even better for the hosts on 18 minutes when a corner from the right was headed in superbly by McLean, who rose highest and planted his effort past the despairing Ederson.
Carrow Road was raucous and just before the half-hour mark, it was 2-0. Pukki evaded the offside trap and rolled the ball across for Cantwell, who tapped past an exposed Ederson.
Aguero's header gave City brief hope but it was extinguished on 49 minutes following Nicolas Otamendi's howler in defence. Otamendi was robbed of the ball in his own area and it found its way to Pukki, who poked past Ederson to restore Norwich's two-goal advantage.
After the match, Guardiola addressed the defensive situation: "John [Stones] and Nico have played together many times and been a huge part of what we have done, but [Vincent] Kompany is now in Belgium, [Aymeric] Laporte is injured and these are the defenders we have at this moment.
"Yes, we have [Fernandinho] and some younger players, but it is not a worry.
"So, we go away, we improve from this and we move on and get better."
Following the Pukki goal, Guardiola reacted by bringing on Kevin De Bruyne and Gabriel Jesus, but the damage was done and Norwich -- not to mention Liverpool -- were left to enjoy an incredible result.
"I can't praise enough the spirit and mentality of my players because it was an unbelievably complicated week," Norwich boss Daniel Farke said.
"It is a great day for us, for the whole club and for the supporters. Carrow Road is absolutely buzzing and it's a win for our owners because they are such kind-hearted people and we cannot ask for better owners."
The prematch odds put the result in perspective, with Norwich City closing as a massive +1800 (18-1) underdog at Caesars Sportsbook, meaning a $100 bet would win $1,800. Manchester City was a -1350 favorite.
Before the match, NBC commentator Robbie Mustoe said of Norwich: "If they end up getting a result, winning this game, it'll be one of the biggest upsets in Premier League history."