Dubois had two goals and an assist to lead Washington, with Jakob Chychrun adding his 22nd of the season. The Capitals scored all three goals in the second period before Vegas mounted a late comeback with third-period goals from Braeden Bowman and Tomas Hertl.
The victory moves Washington within two points of the New York Islanders for third place in the Metropolitan Division and within two of Boston for the Eastern Conference's second wild card. The Capitals are 2-0 since the Olympic break and have won six of their last seven games, while the Golden Knights saw their three-game winning streak snapped despite returning five Olympians.