Washington goalie Jose Theodore was absent Friday for personal reasons and the Capitals called up Michal Neuvirth from their Hershey franchise to face the Canadiens. Neuvirth allowed three goals on 22 shots.
Washington lost for only the second time in eight games.
Eric Fehr gave Washington the lead with a first-period goal, but Montreal responded with three scores in a row to capture its second straight game.
Travis Moen tipped in a shot by Roman Hamrlik early in the second and Tomas Plekanec put the Canadiens in front with a wrist shot.
Cammalleri's power-play goal with 7:31 remaining in the third gave Montreal a 3-1 lead and that score became vital when Brendan Morrison tallied for Washington with 2:32 left.
Carey Price made 32 saves to get the win. Washington's Alex Ovechkin, playing his second game after missing six contests with an injury, got off four shots without registering a point.
Copyright 2009 by United Press International.