Houllier said: "We know what we have to do to get fourth and I am convinced we will get there.
"We have been too unlucky of late for that to continue over the rest of the season. We just have to keep on showing the same attitude and committment and I am confident we will get to where we want to be.
"We've had a difficult season in terms of injuries but I think our football has been good. We didn't deserve to lose at Southampton on Sunday and even their manager was big enough to admit that. We had more chances than they did and more shots on goal.
"We now have a real chance this week to impose ourselves on the league and to get into that top four. There are four or five teams challenging for that fourth place and we will give everything we have to get there."