Roberto Mancini said he disagreed with two penalty decisions as Manchester City's 14-game unbeaten league run came to an end with a 2-1 defeat by Chelsea.
City were leading 1-0 when they were denied a penalty after David Silva was tripped while Joleon Lescott's handball allowed Chelsea to score a late winner.
"The referee was too close to decide this and probably didn't see it," City boss Mancini said of Silva's claim.
"He saw very well their penalty, he was really sure. I don't agree with him."
Chelsea defender Jose Bosingwa appeared to catch Silva just inside the penalty area as City's midfielder tried to skip past him but referee Mark Clattenburg, who was just a few yards away, waved play on.
"It was probably because it was raining and cold that he didn't see the penalty because all the stadium saw the penalty, only he missed it," Mancini added.
Frank Lampard came off the bench to earn Chelsea a vital win which puts them third, seven points behind Mancini's league leaders.
The English midfielder scored after Lescott was penalised for handling the ball following Daniel Sturridge's shot.
Before that, City were reduced to 10 men on the hour when full-back Gael Clichy received his second yellow card and they failed to hang onto a point after Raul Meireles equalised following Mario Balotelli's second-minute opener.
Mancini bemoaned his side's inability to score more than one goal in a first half they dominated for long periods, and admitted that the sending off was the turning point.
"I think we deserved to score two or three goals in the first half because we did a fantastic performance but in football if you don't score you can lose and after the sending off it was difficult to play," he said.
"Chelsea played better when we had 10 players and before that they didn't take any risks.
"I think we are strong enough for the next game [against Arsenal] and I hope we can do another 14 games without defeat.
"December and January will be crucial months for us and it was important not to lose this game. The season is very long, and all the teams can play for the title."