Six minutes into the second period, Steelers trailed 4-0 to goals from Matt Beca (2), Matt Stanisz and Gerard Hanson.
But they came storming back to level the game at 4-4 with 51 seconds to spare.
Ben O’Connor got the ball rolling midway through the second period before Josh pitt gave them further hope shortly before the end of the second.
Stefan Della Rovere scored in the third before Ryan Martinelli struck the equaliser in the final minute. With momentum firmly on their side, Matheson struck the game winner for Tom Barrasso’s men 2.27 into the overtime period.