Carlo Ancelotti believes Manchester United would find it difficult to retain the Premier League title without Wayne Rooney.
The Italian coach hinted United are over-reliant on the England striker and Chelsea's attacking strength in depth gives them the edge over Alex Ferguson's side.
The Chelsea boss faces a Birmingham side unbeaten in 15 games at Stamford Bridge tonight with United sitting on top of the table following their weekend victory over Hull.
Rooney scored all four goals in their demolition of the struggling Tigers and Ancelotti clearly knows the true value of the England star.
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.
"He's a very decisive player for United. But we have possibilities without Didier Drogba because we can put Nicolas Anelka on, another top striker in world football.
"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."
The club's talks with Anelka over a new contract continue, but speculation suggests the two parties are far from agreeing a new long-term deal. The 11-goal Frenchman has 18 months left to run on his current agreement but Ancelotti is "100pc convinced" the forward will remain at Stamford Bridge.
"I think that they are speaking with his agent and they will try to find the right solution for both the club and for him," said Ancelotti.
"I'm confident he'll sign. Anelka is a top player and this club needs to have a lot of top players. It's the same question with Joe Cole. We want to keep him and he wants to stay. There will be a resolution.
"Anelka has told me he wants to stay. He's happy with me. He's happy to work with me, and I'm very happy to work with him. That's a wedding, no? We don't want to break up."
Chelsea have two games in hand on leaders United and Ancelotti believes dropping to third place may have given them a psychological boost.
"Psychologically, it might not be a bad thing for us to be third," he said. "We have to stay focused because we have three games in a week and we need to claim the points. But it's in our hands."
Meanwhile, injured Juliano Belletti has revealed on Twitter Chelsea have blocked his chance of a move to Flamengo.
Belletti, 33, who can play in defence and midfield, is out for a month with a knee injury.
Flamengo had prepared a two-year deal, but could not afford to pay a transfer fee and Belletti said on Twitter: "Chelsea FC said that they are not going to release me before the end of my contract, which expires in June 2010."
Meanwhile, Birmingham boss Alex McLeish admits he is also targeting a striker and a wide midfield player before the transfer window closes.
He is interested in signing Spurs striker Roman Pavlyuchenko and Liverpool forward Ryan Babel.
McLeish said: "Are any other deals close to being completed? There is nothing close but we are trying a couple of things.
"With the Craig Gardner move going through, we have spent a good part of £3m, a long way short of the £20-40m that was bandied about (following the takeover by Carson Yeung).
"I have no intention of spending that amount with the way this team has played.
"But I still believe we have to spend some more money to bring in a striker and a wide man for more cover in the squad before the window closes."
McLeish is under no illusions about the task facing his City against Ancelotti's team, but believes they can play with no fear after their recent run and encouraging performances against the other Premier League big guns.
He said: "We won't be favourites to win this one. Chelsea are in great form as well and I believes they are the team to beat for the title, although Manchester United always come strong in the second half of the season.
"But we've gone to Old Trafford, the Emirates, White Hart Lane, Anfield, Goodison Park and, although we may have not taken a lot of points at those places, we've given good performances.
"We didn't look as if we were out of our depth in any shape or form and it has given the players great confidence and belief in themselves.
"The evidence is there of us going away to these grounds and being able to stand up to the task."