Ovechkin sat out Wednesday's loss to Ottawa with a lower-body injury he had suffered two nights earlier in a setback against Carolina.
The Capitals ended a three-game skid and moved within a point of Florida for the eighth playoff spot in the Eastern Conference.
Mathieu Perreault opened the scoring for Washington 6:58 into the contest and the Capitals took a 3-0 advantage when Jason Chimera and Ovechkin scored 16 seconds apart in the middle period.
Montreal suffered its third straight loss. Carey Price gave up three goals on 23 shots.
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