Allen's previous high in the regular season was 46 saves for the St. Louis Blues in a 4-3 overtime loss to the Chicago Blackhawks on Oct. 13, 2018. He made 51 saves for the Blues in a 2-1 overtime win against the Minnesota Wild in Game 1 of the Western Conference First Round on April 12, 2017.
"It was just a matter of getting some positive vibes going back home," Allen said. "I thought it was a crucial game for us. Obviously, we've been down in the dumps a little bit as a group, and not playing our best hockey. I just thought it was an important game to play well with a lot of effort, and most importantly, get the win."
The Canadiens (6-15-2), who lost six of their previous seven, scored five goals in the third period, three into an empty net. They were coming off a 4-1 loss at the Buffalo Sabres on Friday.
Sidney Crosby had a goal and two assists for his first multipoint game of the season, and Casey DeSmith made 28 saves in his first start since Nov. 13 for the Penguins (10-7-4).
Pittsburgh had outscored opponents 16-2 during the five straight wins, which represented the longest active streak in the NHL. Tristan Jarry had three shutouts, including a 1-0 win at the New York Islanders on Friday, and allowed one goal in each of the other two games.
"Give [Allen] credit. He played really well," Penguins coach Mike Sullivan said. "We threw a lot of pucks at him tonight. We could've had a little bit more net traffic and made his sightlines more difficult, but we could probably say that most nights. That's something that we're always striving to get better at."
Jonathan Drouin put the Canadiens ahead 1-0 on a breakaway. After a pass from Crosby hopped over teammate Kris Letang's stick, Drouin took it the other way before scoring with a backhand through the five-hole at 15:34 of the second period.
"We're obviously not having the year we want," Drouin said. "We have to keep it simple. Be patient. When we get our chances, we get our chances."