Jean-Gabriel Pageau got his first NHL hat trick Sunday night to lead the Ottawa Senators to a fight-filled 6-1 victory over the visiting Montreal Canadiens.
The teams combined for 232 penalty minutes and nine players were given game misconducts.
The Senators have a two-games-to-one lead in the best-of-seven series.
The third period started out with the Senators leading, 2-1, but after Pageau's second goal of the night and a Kyle Turris goal at 7 minutes, emotions overflowed and a line brawl broke out at center ice.
Chris Kunitz scored his second power-play goal of the game 8 minutes, 34 seconds into overtime, off a pass from Sidney Crosby, and the visiting Pittsburgh Penguins shook off an early deficit to beat the New York Islanders, 5-4, in Game 3 of the first-round series.
The Eastern Conference's top-seeded team rode severe ups and downs in taking a 2-1 lead in the series.
"There was a lot of emotion in this game," Kunitz said. "They really came after us."
Jason Zucker scored at 2:15 of overtime to give host Minnesota a 3-2 victory over the Chicago Blackhawks, pulling the Wild within 2-1 in the Western Conference series.
Zach Parise scored for the Wild early in the third period, but Duncan Keith got one back for the Blackhawks with 2:46 left in regulation to force the second overtime in three games.
Detroit's Justin Abdelkader was suspended two games for Saturday's hit on Anaheim's Toni Lydman.
The suspension means Abdelkader must miss Games 4 and 5 of the series between the Red Wings and Ducks. Anaheim leads the series, 2-1.