Manchester City manager Roberto Mancini admits he underestimated Everton after watching his side lose 1-0 at Goodison Park.
Darron Gibson scored the solitary goal of the game after a long-range effort swerved into the top corner of Joe Hart's net, after the visitors failed to capitalise on their dominant possession.
Mancini conceded that he failed to prepare the team for the match and thought the game would be easier for his superstars to succeed in.
"(It's a) bad night for me," Mancini told reporters. "We didn't deserve to lose, but I think there was some of my mistake in this game, we didn't prepare very well for this game and we had a problem."
"It's important for me to know what this mistake is. I didn't prepare well because I thought maybe this game was easier and you know here is never easy, never."
"I didn't prepare well with the training in the last three or four days."
Asked if his players put in the same effort as the hosts, Mancini said: "Yes, the players put everything on the pitch, but I made some mistakes to prepare them in last three days to prepare them for this game."
"(I thought it would be easier) because I thought we played well against Tottenham, we won the last three games in the Premier League and I thought Everton were without three or four important players."
Regardless of the loss, the former Inter Milan coach remained confident that his side have the quality and the time to stay ahead of the chasing pack.
"It is not important, we are on the top, we have 15 games, it is important that next Saturday we win, however, we have time."
Mancini's opposite number, David Moyes, expressed pride after his players came through a tough clash with three points.
He told reporters: "That's as good at Everton as it has been for a long time. The players we were missing says a lot about the club and how they always seem to come and do it, the players have been great tonight."
"We might have played smoother football and played better, but a side we were playing against tonight I think the players deserve a lot of credit. Manchester City are a magnificent team, we had to defend for long periods, especially in the second half."