London, Sep 17: Manchester United manager Sir Alex Ferguson says that it would be "incredible" if Chelsea manager Andre Villas-Boas could win the Premier League at his age.

Villas-Boas, 33, has made a promising start to his Stamford Bridge reign.

"It would be an incredible achievement for someone of his age to do that," the Sun quoted Ferguson, as saying.

"For a young man going to Chelsea it's a hard challenge, but he's done very well and his team have responded," he added.

He also admits that Chelsea be a big threat during tomorrow's game at Old Trafford.

"The Manchester teams are enjoying the publicity of the predictions that the two of us will be involved in winning the league," Ferguson said.

"But in the background lurks Chelsea. Nobody's talking about them and that's an advantage," he added.

Prior to his appointment at Chelsea, Villas-Boas had spent nine months as manager of Portugal's Academica de Coimbra and then a year as manager of F. C. Porto.

While at Porto he became the youngest manager to win a European club title.

His 13.3 million pound move from Porto to Chelsea is the most expensive ever by a manager.

Unusually for a manager at the top level, he has no experience as a professional player. (ANI)