But Houllier is adament that both Cheyrou and Diouf will succeed at Anfield, and also revealed the reasons behind both players lack of appearances of late.
He said: "You need six months to settle into the English game and Bruno and El-Hadji will not be kept out of the first team for long.
"Bruno had a problem recently because he had both his wisdom teeth out. That's why he couldn't be involved in our matches. It's worth pointing out we have not lost a match when he's played. It's as simple as that with him.
"Dioufy only came back from South Africa late last week so couldn't be involved in our game with Fulham."