He became the 23rd coach of the franchise when then-coach Jacques Demers was fired only five games into the season with a 0-5 record.
Habs fans were shocked with Tremblay coaching the team. He didn't have any experience coaching. Worse, his assistant Yvon Cournoyer—another former Habs player—didn't have experience coaching either.
It was a recipe for disaster.
Detroit scored nine goals on Roy. When Tremblay finally pulled Roy out of the nets, the first thing Roy did was tell team president Ronald Corey that it was his last match in Montreal.
Four days later, Roy was traded to the Colorado Avalanche.
These two had a long-running dispute. Before Tremblay coached the Habs, he and Roy almost came to blows in a coffee shop in Long Island. The second time came when Tremblay fired a shot at Roy's throat during practice.
Was Tremblay hardheaded? Almost a year after the Roy incident, Tremblay had a verbal argument with former Canadiens enforcer Donald Brashear during practice prior to a game. Brashear was later traded to the Vancouver Canucks.
Mario Tremblay coached 159 games, with 71 wins, 63 losses, and 25 ties during the two years he was with the team.
Here's what Patrick Roy said when reporters asked his thoughts about Tremblay and Cournoyer when they got hired by the Montreal Canadiens:
“I was watching the news on RDS (Québec Sports Network) and when I saw them appear, I went to the shower. I took a cold shower to make sure that I was really awake...”