Rielly rang a shot off the post at 2:05 of overtime.
The Bruins failed to convert on a power play after Nylander was called for holding at 2:25.
DeBrusk and Charlie Coyle scored the only goals in the shootout.
Maple Leafs defenseman Timothy Liljegren left the game with 41 seconds left in the first after slamming into the corner boards feet first while tied up with Marchand. Keefe said Liljegren is expected to miss “significant time” pending further evaluation.
“We’ve obviously had some pretty good battles with that team,” said Marchand, the Boston captain. “They pushed back. They’re always a great team. Their power play is very dangerous and they kind of took control. … We did a good job regrouping in the third and came out with the win, so it’s good.”
NOTES: Lohrei, who was born in Baton Rouge, Louisiana, when his father, David, was a coach in the ECHL there, became the first Louisiana-born player to play an NHL game. … Bruins defenseman Kevin Shattenkirk had three shots on goal and played 21:23 in his 900th NHL game. … Boston became the second team with a season-opening point streak of at least 10 games this season, joining the Vegas Golden Knights. This is the third NHL season when multiple teams have had double-digit runs, following 2006-07 (Anaheim Ducks, Buffalo Sabres) and 1972-73 (Montreal Canadiens, Sabres). The Ducks and Canadiens went on to win the Stanley Cup in 2006-07 and 1972-73, respectively. … Bruins defenseman Charlie McAvoy served the first of a four-game suspension for an illegal check to the head of Florida Panthers defenseman Oliver Ekman-Larsson on Monday. Boston also played its first game without defenseman Matt Grzelcyk, who was placed on long-term injured reserve Wednesday with an upper-body injury sustained in that game. … Nylander has 14 points (six goals, eight assists) during his streak.