Alex Galchenyuk scored at 3:40 of the first overtime to give the Montreal Canadiens a 3-2 win over the Ottawa Senators, putting them 2-0 up in their Eastern Conference first round series.
Goal-tender Carey Price made 29 saves for Montreal while Andrew Hammond stopped 37 shots for the Senators.
Elsewhere, playing in his first career playoff game, goal-tender Philipp Grubauer kept the Washington Capitals' hopes of a deep playoff run alive, stopping 18 of 21 shots in a 4-3 comeback victory over the New York Islanders.
Trailing by a pair of goals late in the second period, the Capitals received unanswered goals by Alex Ovechkin, Nicklas Backstrom and Jason Chimera to pull out the victory and even the Eastern Conference first-round series 1-1.
Overcoming a game-ending injury to their best player midway through the second period, the Nashville Predators equaled their first round series against the Chicago Blackhawks with a 6-2 win.
The Vancouver Canucks also evened out their series 1-1, using a dominating first period to build a lead then riding the goaltending of Eddie Lack to defeat the Calgary Flames 4-1.