Ovechkin, a two-time MVP who led the NHL with 32 goals this season, crashed the net to score on a power play about seven minutes into the second period to tie the game. Carl Hagelin had put New York ahead 1-0 in the first period — the only puck that made it past Braden Holtby, who finished with 35 saves.
Game 2 of the best-of-seven series is Saturday in Washington.
It's the third consecutive season these two teams are facing each other in the playoffs and the fourth time in five years. The Rangers eliminated the Capitals in seven games in the second round last season.
BLUES 2, KINGS 1
ST. LOUIS (AP) — Defenceman Barret Jackman scored his first career playoff goal with 50.4 seconds remaining, lifting St. Louis over defending Stanley Cup champion Los Angeles for the second straight time.
Jackman, a stay-at-home type who totalled three goals and 12 points in the regular season, joined a rush and scored in transition against Jonathan Quick, last year's playoff MVP. He beat Quick from just inside the blue line for a 2-0 series lead heading to Los Angeles.
The Blues capitalized on a stickhandling goof by Quick to win the opener on Alex Steen's short-handed goal in overtime.
Patrik Berglund's deflection tied it early in the third period for St. Louis, which was swept by the Kings in the second round last season while getting outscored 15-6.
Dustin Brown scored for the Kings, who'll try to rebound in Game 3 Saturday night.
SENATORS 4, CANADIENS 2
MONTREAL (AP) — Craig Anderson made 48 saves in a spectacular goaltending performance in Game 1. Jakob Silfverberg and Marc Methot scored early in the third period to lift the Senators into the lead.
Game 2 set for Friday night at the Bell Centre.
Erik Karlsson and Guillaume Latendresse also scored for the Senators, who were outshot 50-31 but saw Anderson easily win the goaltending duel with Carey Price, who was beaten twice through the pads.
Rene Bourque and Brendan Gallagher replied for Montreal, which set a team record for shots in a regulation-time playoff game.
Montreal centre Lars Eller was wheeled off on a stretcher bleeding heavily from the nose and was taken to a hospital with what the team said were head and facial injuries after he was caught with a shoulder to the face on an open-ice hit from Senators defenceman Eric Gryba.
Red Wings 5, Ducks 4, OT
ANAHEIM, Calif. (AP) — Gustav Nyquist's power-play goal at 1:21 of overtime after the Red Wings blew a three-goal lead in the third period to even their playoff series with Anaheim.
Johan Franzen scored two goals and Damien Brunner had his first Stanley Cup playoff goal and two assists for the Red Wings, who survived a third-period collapse with a timely goal from Nyquist.
Bobby Ryan scored the tying goal with 2:22 left in regulation for the Ducks, who also got goals from captain Ryan Getzlaf and Kyle Palmieri while erasing Detroit's 4-1 lead with a phenomenal surge in the final minutes.
Game 3 is Saturday night at Joe Louis Arena.