Aston Villa boss Gerard Houllier has offered four reasons for the success of Sir Alex Ferguson.

Houllier faces Ferguson's Manchester United today.

Houllier said: "There are four things with him. One, he knows football inside out.

"Two, he is an absolute workaholic. You can ring him at the office at 8am and know he will be there.

"Three, he is very loyal to his players, club and friends. You never heard a word of criticism against Eric Cantona over that kung-fu kick.

"And four, his capacity to change. He has not said 'This is the way I do it'. He has evolved."