Ferguson dismissed Scolari's chances of repeating the unprecedented success Jose Mourinho brought to the Stamford Bridge club, who are expected to be United's main challengers for silverware once again this term.

"I'm not concerned about Chelsea," Ferguson told the Daily Mail. "Avram Grant did a good job and Mourinho won the title two years in a row and beat us in the FA Cup final.

"So there's no-one who can improve on Mourinho's record really."

Ferguson suggested Chelsea would struggle to push champions United as hard as they did last season with a squad he considers to be past their best.

He said: "They are an experienced side. I'm not saying necessarily that they're old because with the modern-day training methods, you should be playing in your 30s.

"What I'm saying is that I don't see outstanding progress coming from a team that's in their 30s."

Ferguson had kinder words for Arsenal and Liverpool, who he expects to complete the top four in the Barclays Premier League again this season.

United will be bidding to win their 11th Premier League title under Ferguson, a challenge that is set to be spearheaded by star striker Wayne Rooney.

Ferguson experimented with Rooney's position last season, often deploying him in a wide role.

Although the England forward worked hard for the team, his goal return was below par.

Ferguson said: "I think I have to take a bit of responsibility for it. He's sacrificed himself and never complained about it, which says a lot for the lad.

"But we kept using him in different positions. We need to define his role better."