Senators 6, Canadiens 1
Craig Anderson made 33 saves and rookie Cory Conacher scored two goals as visiting Ottawa ousted second-seeded Montreal in five games.
Erik Condra had a goal and two assists and Zack Smith, Kyle Turris and captain Daniel Alfredson also scored as the Senators claimed the final three games of the best-of-seven series.
Seventh-seeded Ottawa became the first Eastern Conference team to advance to the second round.
Defenseman P.K. Subban scored the lone goal and backup goaltender Peter Budaj made 23 saves for the Northeast Division champion Canadiens, who again were stymied by Anderson and the league's best penalty-killing unit.
Montreal failed to score on four straight power-play chances and also yielded a backbreaking short-handed tally to Turris.
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Penguins 4, Islanders 0
Tomas Vokoun turned aside 31 shots in his first postseason appearance since 2007 and captain Sidney Crosby collected a goal and an assist as host Pittsburgh seized a 3-2 advantage in its Eastern Conference first-round series with eighth-seeded New York.
Kris Letang scored a goal and set up another while fellow defenseman Douglas Murray and Tyler Kennedy also tallied.
Pascal Dupuis, Evgeni Malkin and Jarome Iginla each notched an assist to extend their respective point streaks to six games for the top-seeded Penguins, who will look to clinch the series on Long Island in Game 6 on Saturday.
Playing in place of the ineffective Marc-Andre Fleury, Vokoun showed no signs of rust en route to his second career postseason shutout.
The 36-year-old entered the contest with a 3-8 mark in the playoffs - with all 11 decisions coming while he was a member of the Nashville Predators.
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Blackhawks 5, Wild 1
Marian Hossa scored twice and added an assist as host Chicago cruised into the second round of the Stanley Cup playoffs.
Marcus Kruger added a goal and an assist while Patrick Sharp and Andrew Shaw also scored for the top-seeded Blackhawks, who completed a five-game series victory over Minnesota with their most dominant performance. Corey Crawford made 21 saves.
Torrey Mitchell had the lone goal for the eighth-seeded Wild, who saw their first playoff appearance since 2008 come to an end with only one victory.
Josh Harding, who left Game 4 after the first period with an injury, was pulled after allowing three goals on 18 shots.
Hossa opened the scoring with 4:21 remaining in the first period when he one-timed a feed from captain Jonathan Toews, who registered two assists for his first points of the postseason.
At 6:26 of the second, Hossa came out from behind the net to grab a rebound and slide it around Harding, ending the Minnesota netminder's night.
Shaw scored 35 seconds after Mitchell got the Wild on the board midway through the second and Sharp added his fifth of the series during a power play in the third, collecting the rebound of Hossa's shot and chipping it over Darcy Kuemper, who made 13 saves in relief.