At 6:52 of the first period, Brad Marchand was called for a tripping penalty on a shorthanded breakaway by Boone Jenner 14 seconds into the Bruins' first power play of the game, the second time they've been called for a shorthanded penalty shot in the 2019 Stanley Cup Playoffs.
The Bruins had a 1-0 lead on David Pastrnak's one-timer from the left face-off circle at 3:33, and a goal on the penalty shot would have erased their advantage.
Instead, Rask knocked away the shot with his stick hand, allowing the Bruins to resume their power play.
Patrice Bergeron scored 26 seconds later.
"It worked out well for us, that sequence of events," Cassidy said.
Perhaps no save was bigger.
"Probably No. 1, 2, 3, I think," forward Sean Kuraly said of where he would rank that moment in the game. "It's huge. It's 1-0 at the time. He was huge for us tonight. He was, I think, our best player."
Rask finished with 39 saves on 40 shots, the lone goal a controversial one. The puck deflected off the protective netting, and the Bruins slowed their play, believing it was about to be called dead. But Artemi Panarin wristed it past Rask, and the goal was counted. The NHL cited Rule 38.4 (ix), which states that "video review shall only be permitted on goals that hit the spectator netting if the puck is directed immediately into the goal."
Even Rask didn't know exactly what happened.
Quipped the goalie, "If I saw it, then I would have probably slammed the sticks and chased the refs."
He didn't. And ultimately, he didn't need to do so.