Ovechkin recorded his 13th goal of the season and fifth in three games to help Washington improve to 9-0-1 at home this year.
The Southeast Division-leading Capitals (13-7-3) were without several players due to injury, including high-scoring wing Alexander Semin, who has an injured back.
The limited bodies forced Washington to bring players up from their minor league system to fill out the roster.
Washington coach Bruce Boudreau commended his player for a good team effort.
"There should be seven or eight guys pretty happy in that (locker room)," he said. "I thought they all contributed."
Ovechkin carried the Capitals with three goals and an assist in a 5-3 victory over Atlanta on Wednesday, but received more help on Friday.
Goaltender Jose Theodore recorded his first shutout of the season with 28 saves.
In other National Hockey League games, it was: Hurricanes 3, Flyers 2 (in overtime); Sharks 6, Stars 2; Bruins 7, Islanders 2; Wild 4, Lightning 2; Ducks 1, Blackhawks 0; Coyotes 2, Avalanche 1; Sabres 4, Penguins 3; Predators 4, Thrashers 3 (in OT); Red Wings 5, Blue Jackets 3; and Rangers 4, Panthers 3 (in a shootout).
In Washington, Tomas Fleischmann opened the scoring when he took a pass from Michael Nylander and beat Jaroslav Halak at 11:03 in the first period. Ovechkin scored three minutes into the third and Dave Steckel followed with a goal five minutes later.
Halak finished with 27 saves for Montreal, which fell to 12-6-4 and has now lost three of its last four games.
"Definitely we let our guard down after beating Detroit (on Wednesday) and maybe thought we were a better team than we are," said Montreal forward Tom Kostopoulos.
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