Anton Forsberg made 24 saves for the Senators (24-20-4), who had won five of their past seven games.
Morgan Geekie gave the Bruins a 1-0 lead at 2:06 of the second period. Defenseman Brandon Carlo fed a pass from the half wall to Pastrnak behind the Ottawa net. He received the pass on his backhand, quickly transferred to his forehand, wrapped the puck around the net and found Geekie on the far post for the backdoor tap-in goal. It was his 13th of the season.
“I just tried to get open and he put it right on my tape,” Geekie said.
Boston went 4-for-4 on the penalty kill, including a crucial 5-on-3 for 32 seconds midway through the third period to secure its one-goal lead.
“Some nights it’s not going to go your way, and some nights it will,” Bruins coach Joe Sacco said about the penalty kill. “There was a strong focus tonight for us, making sure that we were trying to cut off the top, trying to keep it to the outside. We didn’t do a good enough job (against the Devils) keeping the puck to the outside. I thought our seam coverage was better tonight and then you need some saves. Forecheck was pretty good too up ice against their entries, trying to deny the blue line as best we can and pressure them before they can set up.”
Ottawa was disappointed with its lack of production on the power play.
“We had some good looks. When your guys aren’t scoring it probably affects them on the power play as well, maybe even more,” Senators coach Travis Green said.
Pastrnak scored into an empty net with five seconds remaining for the 2-0 final.
David Perron returned to the lineup for the Senators. The forward had not played since Nov. 23 because of an upper-body injury. He was on the third line with Ridly Greig and Zack Ostapchuk. Perron logged 11 minutes of ice time in only his 10th game of the season.
NOTES: Boston's John Beecher played his 100th NHL game. ... Trent Frederic returned to the lineup after missing two games due to illness for Boston. ... Pastrnak tied Marc Savard (five) for the fourth-most six-game assist streaks in team history, behind Ray Bourque (15), Bobby Orr (10) and Adam Oates (six) . . . Korpisalo (15 starts) required the fifth-fewest starts in franchise history to record three shutouts, behind Frank Brimsek (six starts), Tiny Thompson (seven), Terry Sawchuk (nine) and Hal Winkler (10). ... Boston has played six sets of back-to-backs and is 5-0-1 in the second games this season.