O'Neill said: "Michael Owen obviously provides a threat to us. Johan (Mjallby) has played against him and I think our players are well aware of the danger. He is a top class player and has to be watched of course.
"Even if you do watch him carefully, as we would want to do, there are going to be moments when he will escape because that is the type of player he is. He is having an excellent run at the moment so, of course, we have to be careful. "I would be delighted if Liverpool didn't score at our place in the match but with the sort of form Owen is in, that will be hard for us."
Celtic's hopes of victory, though, will be boosted by the news that Henrik Larsson will be in contention for a starting place tomorrow night.
O'Neill added: "Henrik has done a few days training and is feeling not too bad. He's feeling good within himself and is raring to go, so I'll have a look at it tomorrow."