Lundqvist's work between the posts ensured Brassard's shot off defenseman Steve Oleksy midway through the second period held up as New York forced a seventh and deciding game in its Eastern Conference quarterfinal series.
Lundqvist was especially busy in the game's final minute as the Capitals pulled their goaltender to add an extra attacker.
But Lundqvist was up to the challenge as the Rangers held off the final onslaught.
Braden Holtby stopped 28-of-29 shots for the Capitals, who will seek to win the series at home in Monday's Game 7.
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