Houllier said: "It's going to be a fantastic atmosphere. We've played in Barcelona, Roma and Manchester United several times and they all had more spectators in their grounds so we are used to it.
"I have heard all about the atmosphere but when you are a player, you wish to play in that kind of environment.
"If you don't like playing at Celtic Park you must not like playing at all. There are good connections between both sets of fans and when we hear the song "You'll Never Walk Alone", we will wonder if we are at their ground or ours."