JOHANNESBURG (AFP) - Manchester United manager Sir Alex Ferguson has warned Luiz Felipe Scolari that he faces a battle to inspire his ageing Chelsea squad to repeat the feats they enjoyed under previous Stamford Bridge manager, Jose Mourinho.

Scolari, currently in Guangzhou, China, with Chelsea as part of their pre-season preparations, succeeded Avram Grant at the English Premier League club this month after resigning his post as Portugal coach at Euro 2008.

The Brazilian arrives in England with a top-class reputation having won the 2002 World Cup with his home nation, but United manager Ferguson, whose team beat Orlando Pirates in Durban, South Africa, on Tuesday believes restoring Chelsea to the top of the tree will not be easy for Scolari.

And he admits that 'Big Phil' faces a daunting challenge if he is to emulate the feats of Mourinho -- the self-styled Special One -- at Chelsea.

Ferguson said: "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 his record really.

@They would have to go beyond Mourinho's performance to really worry us.

"Scolari is fortunate as Chelsea have a lot of experience and that was the one thing I was a bit concerned about last season, but I don't know how far that team has got to go.

"It's hard to see where there's going to be a big improvement with a team that's really very experienced. 'Plateau' is maybe not the word, but how can they (Chelsea) accelerate beyond what they've done up to now?"

Premier League and European champions United face Chelsea in September at Stamford Bridge in their first clash since the Champions League final in Moscow in May, which United won on a penalty-shoot-out.

And Ferguson is confident that his team has the necessary youth to stay ahead of Chelsea in the race for more silverware in the coming season.

He said: "When you see the ages Chelsea have got, apart from Salomon Kalou and John Obi-Mikel, 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 thirties. What I am saying is that I don't see outstanding progress in a team that's in their thirties.

"I don't know Scolari. We played against him when we won the World Club Championship in 1990 and he has managed a lot of clubs. But he is experienced, having won the World Cup and managed Portugal, and that's one thing he has in his favour."