The Reds claimed a morale-boosting 2-0 victory over Sunderland on Wednesday to keep alive their faint hopes of winning the league title for the first time since 1990.
They lie joint-second in the table along with Chelsea on 58 points, four behind leaders and title holders Untied, who still have two games in hand.
"United have a good team and good squad, but it is football so you never know," Benitez told Sky Sports 2.
"We have to keep going and approach every game thinking about the three points and we will see what happens.
"We know that it will be difficult, but we still have our chances. We know that each game will be very important."
Liverpool will have a chance to reduce the arrears when they face United at Old Trafford on March 14th.
"Old Trafford will be crucial. We want to reduce the gap," the Spanish coach added.