And Houllier compared the ex Sedan star to Arsenal's Patrick Vieira, a comparison he grew familiar with in France.
He said: "I thought it was better to have the best team right away so I called the chairman and asked if he could come early.
"The best is yet to come for Salif because he is strong and powerful but he needs to come to terms with attitudes here.
"The movement of the game is different, with more pace and more aggression. He needs to get used to that because he has the same qualities as Patrick Vieira."
"Our scouts spotted him and even Michel Platini advised me to have a look at him. He's an intelligent lad and great in the dressing room."