Everything went right for the defending champion Washington Capitals on opening night Wednesday, and the Boston Bruins were on the embarrassing end of a 7-0 loss.

Bruins forward Brad Marchand took exception to how Lars Eller acted after he scored Washington's seventh goal at 10:52 of the third period. On their next shift a little more than three minutes later, Marchand pummeled the Capitals forward, leaving him with a gash on his head.

Capitals coach Todd Reirden said Eller was being looked at after the game.

"His celebration was unnecessary," Marchand told reporters after the game. "He took an angle in front of the bench and celebrated in a 7-0 game, so I just let him know."

Marchand is a two-time All-Star, but also likes to push the limits. He was warned in last season's playoffs about licking opponents.

It was Eller's first fight and he didn't have much of a chance. Marchand left the game with an instigator minor, a fighting major and a 10-minute misconduct. Eller, who scored the Cup-clinching goal in Game 5 against the Vegas Golden Knights in June, got five for fighting.

"He's a proud guy," Bruins coach Bruce Cassidy said of Wednesday's fight by Marchand. "I think Eller celebrated a little on a 7-0 goal. It's his prerogative, and Marchy let him know that's not acceptable."

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Reirden said he was disappointed by Marchand's actions and wondered whether the league would look at it.

"That was something that is unfortunate, and I feel unjust and certainly a player that wasn't prepared for that in Lars," he said. "I think there was an early start to the fight as well."