Wagner thought he gave the Bruins a lead 20 seconds into the first period, but the goal was disallowed because of goaltender interference against Sean Kuraly. The call was upheld after video review.
But Wagner took advantage of his second chance to make it 1-0 when Noel Acciari found him in the slot at 10:10. It was fitting tribute for Wagner to his grandfather, who died Friday.
"Maybe he was watching out for me, making the puck follow me around, who knows," Wagner said. "But he was probably laughing after that first goal was disallowed. He would drive me around when my parents couldn't, went to all my games, watched all these games even up until the Winter Classic [on Tuesday], so it means a lot."