Roy, who won two Stanley Cups during 10 years with the Canadiens as their goaltender, was a finalist for the Montreal coaching job in the off-season before being hired by the Avalanche.
After being traded to the Avs in 1995, Roy also led them to two NHL championships. They improved to 12-1-0 in their first 13 games with him behind the bench.
Gabriel Landeskog provided a goal and an assist.
Brendan Gallagher scored and Peter Budaj made 27 saves for Habs, who dropped a second consecutive game.