Roberto Mancini expects Manchester City to face a tougher task against Chelsea on Sunday after the London club sacked Roberto Di Matteo and replaced him with Rafael Benitez.
City, who start the weekend at the top of the Premier League, are looking to bounce back from the bitter disappointment of going out of the Champions League after being held to a 1-1 draw by Real Madrid on Wednesday.
But Mancini believes City's 12-match unbeaten league run this season is under threat after the events at Stamford Bridge this week.
"Usually when one team changes a manager, the game after for the opponents is very difficult," the Italian told a news conference in Manchester on Friday. "For us, I think it is more difficult."
He added: "Chelsea are one of the best teams in England, in Europe. They have won everything in the last 10 years.
"Playing against them in London is always a good game. To win there would be important for us. Chelsea is a good team with Di Matteo and will be a good team for Benitez. They have good players.
"Until three games ago, they played fantastic football and were on the top of the table."
On Di Matteo's dismissal, Mancini said: "I am very sorry for him because he won the Champions League six months ago, but this is our life as a manager."
Having been eliminated from the Champions League, the pressure is on City to defend the league title they won last season.
The champions head for London amid reports the manager will not be given new funds to bolster his squad in the January transfer window, although he still retains the support of the club.
"We didn't talk about this," said Mancini when asked about speculation over his spending plans in the New Year.
Captain Vincent Kompany is a doubt for the game after badly twisting his knee against Madrid.
"We need to wait until tomorrow (Saturday)," said Mancini when asked about the defender. "I hope we can recover him for Sunday because Vinnie is strong."
However, Gael Clichy, who missed the match against Real with an ankle problem, is in line to return at left-back.
Without Clichy, Mancini started with a back three against Madrid, with Aleksandar Kolarov at left wing-back, before deploying Pablo Zabaleta at left-back in a 4-4-2 formation after a tactical change.
But Mancini denied that City fell behind because of his fondness for a 3-5-2 formation, attributing Karim Benzema's goal to individual errors.
"You talk always about three, about four (at the back)," he said.
"There is no change. When we concede one goal on Wednesday, we were five against two in the box. It is one individual mistake. You cannot concede a goal when you are five against two in the box. We need to work on this."
Reflecting on City's Champions League exit at the group stage for the second successive season, Mancini said City still needed time to establish themselves as a major European force.
"It is clear we are disappointed because we have players who deserve to play in Champions League," he added.
"Together we made some mistakes. We can't change this now. We can't cry for this. We need time for this. It is easy to be strong when we win every game.
"We should be strong when we can't win or we can't play in the Champions League in February. By this situation we can improve as a team and as a club."