The Reds currently sit third on the table with 66 points and need to continue picking up points if they are to clinch a Champions League spot for 2017/18.
"All the sides have a chance," Lucas told Sky Sports ahead of Monday's clash with Watford.
"We know we won't be top four if we don't win games - that is the pressure we have at this moment.
"Of course, some teams will play each other, which means one or both will drop points, and we just have to do our best to win our next four games.
"If we win the next four games, I think the chance to be in the top four is likely, but you never know.
"We just have to win and see how it will end."