The Blues had won just once in nine games prior to last weekend's victory over Blackburn.
From a position of superiority at the top of the table, Chelsea are now fourth, seven points adrift of leaders Manchester United and Mancini's City, who are scrapping it out at the summit now.
Yet Mancini, who claimed earlier this season that Chelsea would retain their crown "easily", does not feel Carlo Ancelotti's men can be written off just yet.
"Chelsea could come back again," said the Italian ahead of City's trip to Aston Villa. "Maybe at this moment Manchester United are better than them but their problem has been to have so many players injured.
"When they get them all back they have a good team."