Alex Ovechkin scored twice in the third period to tie the game for the Capitals (23-10-9), who have 10 consecutive wins against the Senators since Jan. 24, 2017 (a 3-0 loss). Vitek Vanecek made 20 saves.
"I thought we just stayed with the game the entire game regardless of the score," Washington coach Peter Laviolette said. "We thought if we could get one, then one might lead to two and then we'll figure out how to get a third. Defensively, I thought we were good all night. Offensively, I thought we got better as the game went on."
Thomas Chabot and Zach Sanford scored for the Senators (11-20-3), who have lost three straight. Murray made 30 saves after missing two games with a non-COVID-19 illness.
"Give them credit, but at the same point we left Ovechkin open in the slot twice and he isn't going to miss those," Ottawa coach D.J. Smith said. "And then in overtime it's a tough turnover."
Ovechkin tied it 2-2 at 9:43 when he scored off a pass from Backstrom behind the goal line. Play continued for 16 seconds until it was halted and ruled a goal.
Asked if he knew the shot went in, Ovechkin said, "No. I thought it hit the crossbar, that's why I tried to play until the whistle."
Ovechkin made it 2-1 at 1:39 on the rebound of Trevor van Riemsdyk's shot. The forward has scored eight points (five goals, three assists) in a seven-game point streak and is one goal from his 16th 30-goal season in the NHL.
"You get a 2-0 (lead) going into the third. You know they're coming with a push," Smith said. "We sat back into our zone. We've got to keep pucks going north, and it ends up, after a long shift mind you, 'Ovi' finds a way to score."