Chris Kunitz started Pittsburgh's third-period surge with his 18th goal of the season and Sutter beat Boston's Anton Khudobin twice in less than four minutes, including the game-winner with 2:03 remaining.
Marc-Andre Fleury stopped 14 shots for the Penguins, who broke loose late against the NHL's best defensive team.
Zdeno Chara and Tyler Seguin scored first-period goals for the Bruins. Khudobin made 31 saves and the Bruins kept Pittsburgh's high-powered offence in check until the final minutes of a matchup between two of the Eastern Conference's best teams.
He's only 17 but he can see the ice so well and he moves the puck and goes to the open ice all the time, so I just think he's a player that is ready to play in the NHL. I'm really looking forward to coaching someone like this.
— U.S. National Junior Team coach Ron Wilson on Auston Matthews, the projected No. 1 pick of the 2016 NHL Draft