Chelsea boss Carlo Ancelotti believes Manchester City will challenge his side for the Premier League title this season.[LNB] Carlos Tevez's excellent second-half winner proved the difference between the teams on Saturday and lifted City to within four points of their opponents, who remain top of the table.[LNB]City boss Roberto Mancini claimed on Friday Chelsea would retain their title "easily" and continued to tip them for glory in May after Saturrday's game, but Ancelotti expects a genuine challenge to come from his fellow Italian's team.[LNB]"They are fantastic players, a very good squad. They can fight for the title," he told Match of the Day.[LNB]Next up for Chelsea is a Champions League clash at home to Marseille before they take on Arsenal at Stamford Bridge and then travel to play Aston Villa at Villa Park, where they lost 2-1 last term.[LNB]But Ancelotti did not seem too concerned to be heading into those games on the back of a first defeat of the season.[LNB]"We lost also last year here, it's not a good pitch for us," he said. "But we stayed at the top of the table, every game is a big test for us.[LNB]"Strange performance, but it can happen you are not able to score, this is football.[LNB]"You have to play against a strong team with a good performance. If you don't play at your best it's normal you don't score a goal."[LNB]Chelsea went into the game having scored 21 goals in their opening five league games but were unable to break down a well-organised City defence.[LNB]Ancelotti even took off leading striker Didier Drogba in the 75th minute, bringing on Daniel Sturridge, a sign of how little joy his side were having up front.[LNB]And he admitted his opposite number had got his tactics spot on.[LNB]"We didn't play how we wanted. We suffered the pressure in midfield that Man City put on us," he added.[LNB]"They won a lot of tackles in midfield so we conceded a lot of counter-attacks.[LNB]"We were not able to use speed in our play because there was no space.[LNB]"We played too complicated in the opponents' half so we didn't have a chance to score.[LNB]"I think that they used a good tactic to play against us. They wanted to do counter-attacks and they did some counter-attacks very well, very quick."