BOSTON (AP) — Jeremy Swayman stopped 21 shots in his first game since signing a new contract, and Mark Kastelic had two goals on Thursday night as the Boston Bruins scored four times in a row to overcome an early deficit and beat the Montreal Canadiens 6-4.

Elias Lindholm and Cole Koepke each had a goal and two assists for Boston, which lost 6-4 to the Florida Panthers in its season opener on Tuesday night. Charlie McAvoy and David Pastrnak also scored to help the Bruins open a 5-2 lead.

Brendan Gallagher scored twice for Montreal, the second with four minutes left to make it a one-goal game. Kaiden Guhle had a goal and an assist and Cayden Primeau made 23 saves for the Canadiens, who beat Toronto 1-0 on Wednesday night in Montreal.

Canadiens: Opening the season with games on back-to-back nights, Montreal didn’t have the energy to keep up with Boston.

Bruins: After losing their opener in Florida with Joonas Korpisalo in net, a game they trailed 5-1 in the second period, Boston looked more at home with Swayman. The goalie remained unsigned this summer and missed all of training camp before agreeing to an eight-year, $66 million deal on Sunday.

Montreal scored twice in the third period, cutting a three-goal deficit to 5-4 on Gallagher’s goal with four minutes left. But Kastelic netted his second of the game just 17 seconds later.

The Bruins outshot Montreal 23-11 in the first two periods but the Canadiens held a 14-6 edge in the third.

Montreal returns home to face Ottawa on Saturday. The Bruins host the Los Angeles Kings on Saturday for the middle of a three-game homestand.