The Tykes are fourth from bottom in the table, one point above the drop zone, while the Seasiders are two places and a couple of points better off.
Hassell said: "It's a big game for us. It's a must-win game.
"If we get the three points on Saturday it will put us above Blackpool. That is massive for us.
"We have to make sure that we beat the teams around us. That's how we are approaching the game and all we can do really.
"We are going into every one of our remaining matches to win."