If Baros is ruled out, it will leave Juan Pablo Angel as O’Leary’s only available senior striker, with Kevin Phillips already ruled out with a calf muscle pull after having a scan.

O’Leary had intended to operate two out-and-out strikers and continue to buck the growing trend of teams operating with a 4-5-1 formation.

O’Leary said: “Milan has taken a bang down the bottom of the tendon. He felt it after the game, was still feeling it on Wednesday and missed training on Thursday. We’re just hoping it will improve, or it mucks my plans up big style.

“I want to go to Chelsea, play with two strikers and have a go. But if Milan is out, it will makes it difficult for us. It will leaves me with just Juan Pablo Angel as a striker as Kevin Phillips has got no chance.

“He’s had a scan which has shown a calf muscle pull and we don’t even think he’s got a chance for the Middlesbrough game the following weekend.”

O’Leary still wants his side to approach the Stamford Bridge encounter with the leaders in a positive frame of mind even if Baros is sidelined.

He said: “We’ll be written off by everybody expecting a home win, but I just want us to be positive about the game. I don’t want us going down there with an ‘as long as we don’t get beaten’ attitude.

“We’ve got to go down there, be positive, be brave, and be willing to accept the ball and want the ball. You can’t go there and think: ’Oh my God, we’re playing Chelsea’ and just give it back to them.

“We need people to go out there and relish the occasion. While we know we’ve got to defend right, or we’re going to get done, we’ve got to go out, take Chelsea on, and ask them questions.”