Novak, who also had an assist, won it on a wrist shot from the right circle off a pass from Evgeni Malkin on a 2-on-1.
Malkin had a goal and two assists, Erik Karlsson and Kris Letang each had two assists, and Arturs Silovs made 20 saves for the Penguins, who opened their season with a 7-0 win at the Philadelphia Flyers on Wednesday.
Nick Suzuki had a goal and three assists, Cole Caufield scored twice, Ivan Demidov and Chris Kreider each had a goal and an assist, and Lane Hutson had three assists for the Canadiens, who won their season opener 3-2 against the Toronto Maple Leafs on Tuesday. Jakub Dobes made 24 saves.
Suzuki set up two goals in 24 seconds with Dobes pulled for the extra attacker to tie it late in the third period. He first sent a pass from behind the net to Kreider for a one-timer in the slot, cutting it to 5-4 with 1:08 left, then set up Demidov at the right post with a pass through the crease to tie it 5-5 with 44 seconds remaining.
Caufield put Montreal ahead 1-0 on its second shot on goal of the game at 3:49 of the first period, skating into the right face-off circle for a wrist shot past Silovs' blocker.
Malkin tied it 1-1 on a power play at 14:07 of the first period with a backhand shot off a rebound from Letang to score for the second time in the first two games of his 21st NHL season.
Declan Carlile gave the Penguins a 2-1 lead 32 seconds into the second period on a wrist shot from the right circle.
Samuel Girard made it 3-1 at 7:59 with a wrist shot at the top of the crease off a backhand pass from Sidney Crosby.
Novak sent a wrist shot over Dobes after taking a pass from Egor Chinakhov on a 2-on-1, extending the lead to 4-1 at 14:01.
Ben Kindel then pushed it to 5-1 by deflecting a point shot from Karlsson on a power play at 15:32.
Suzuki cut it to 5-2 at 18:46 on a backhand shot after splitting the defense.
Caufield pulled Montreal to within 5-3 with a wrist shot from the high slot at 3:31 of the third period.
Chinakhov seemed to extend the lead at 5:25, but the play was ruled offside after a challenge from the Canadiens.
Montreal defenseman Alexandre Carrier left in the second period with an undisclosed injury.
