Ancelotti hinted United are over-reliant on the England striker and Chelsea's attacking strength in depth gives them the edge over Sir Alex Ferguson's side.
When asked if United could win the title if they were denied Rooney's services through injury in the months ahead, Ancelotti said: ''Without Rooney it'd be difficult. He's the best striker at Manchester United, and one of the best strikers in the world.
''He's a champion, a world-class player, and not only just a finisher but a team player. I saw him play left-wing at times last year, coming back to help the team out defensively.
''Drogba is an important player for us, but we've played very well without him. This means, as I've always said, we have a very good squad. Without him we have the possibility to put other strong, fantastic players in the team.
''When we were without the suspended Didier earlier in the season in the Champions League, Nicolas did very well. Now we have had Nicolas and Daniel Sturridge doing well for us in the last month, so we have quality without Didier. We can use other players in those forward areas.''