The Prince Albert Raiders are one win away from advancing to the Memorial Cup.
Ian Scott made 36 saves to pick up his fifth shutout of the playoffs.
The lone goal was scored by Brett Leason early in the third period on a breakaway. Leason has now scored in four straight games and has a seven-game-point scoring streak.
David Tendeck stopped 25 of the 26 shots he faced.
The Raiders can win the Ed Chynoweth Cup on Friday when Prince Albert and Vancouver meet in Game 5 in Langley, B.C.