Grzelcyk, though, never left, and two minutes later he was back out for his second shift and then his third and then it seemed that the hit would fade into the background of a game sure to have its twists and turns on the way to 60 (or more) minutes of action.
Except it didn't. Because it was Grzelcyk who didn't fade, blossoming under the lights of a rink he once got to use as his personal playground, one in which he grew up -- literally.
[WATCH: Hurricanes vs. Bruins Game 2 highlights | Complete series coverage]
He scored twice in Game 2, once at 15:22 of the first period to open the scoring for his Boston Bruins, one at 17:56 of the second on the power play, to give the Bruins a four-goal advantage in a game they would eventually win 6-2, to take a 2-0 lead in the best-of-7 Eastern Conference Final against the Carolina Hurricanes.
Game 3 is at Carolina on Tuesday (8 p.m. ET; NBCSN, CBC, SN, TVAS).
Video: CAR@BOS, Gm2: Grzelcyk's shot sneaks past Mrazek
The defenseman did what he surely did dozens or hundreds of times in rinks all over the area, as teammate Charlie Coyle had once done in his cul-de-sac in Weymouth, Massachusetts: He played the hero in the Stanley Cup Playoffs.
"Just to be on this stage and be a part of the team, I kind of pinch myself every day," Grzelcyk said.
Grzelcyk, who grew up in Charlestown, Massachusetts, a mile or two from the Garden -- once the old Boston Garden, and then TD Garden -- had gotten the call every now and then from his father, John Grzelcyk, that there was a chance to play on the Garden ice, a chance to play-act all the dreams that most kids never get to fulfill. John Grzelcyk, who has worked on the Bull Gang at the Garden since 1967, the team that converts the arena from hockey rink to basketball floor to concert venue, gave him access that most kids could only imagine.
John is at the Garden almost every day, voluble and ever-present. On Sunday, Mother's Day, Grzelcyk's mom was there too, sitting in the stands, a person that Grzelcyk called "probably my best friend" after the game.
Which meant a lot, given that she was able to see him play, see the goals, likely wince seeing him taking that hit and breathe better when he returned to the ice.
"He's a gamer," defenseman Charlie McAvoy said. "We had no doubt he was going to come back and play his game -- he always does. He's a rock for us and he played awesome tonight. I couldn't be happier for him to break through and get a couple."
Grzelcyk had already scored in the playoffs, a goal in Game 2 of the Eastern Conference Second Round against the Columbus Blue Jackets. But defenseman Connor Clifton, who scored the eventual game-winner at 3:46 of the second period, had not. It was the first goal of his NHL career, and it gave the Bruins a notable achievement.
With Clifton added to the list of scorers, the Bruins have gotten goals from 19 different players in the playoffs. Brandon Carlo remains the lone player to have skated in more than six games not to have scored.
It is exactly what the team didn't have last season, when the Bruins lost in five games in the second round to the Tampa Bay Lightning, when their scoring was focused on the top line of Brad Marchand, Patrice Bergeron and David Pastrnak. It is different this season, with the defensemen chipping in, and with the third line transformed, led by Coyle, who had three assists in Game 2, and Marcus Johansson, who had two.
It changes the dynamic. It changes the way in which other teams defend them. It has been instrumental in getting the Bruins this far -- and possibly beyond, as the teams head to Raleigh for Game 3.
Video: CAR@BOS, Gm2: Grzelcyk nets second goal on power play
"We went through it a bit last year against Tampa," coach Bruce Cassidy said. "We weren't getting the goals, so you press with maybe your top guys instead of letting the play or the game just come to you. I think this year because we've scored a lot more up and down the lineup, it's just a little easier to roll lines and look for your matchup."
Not that Grzelcyk is generally the player that Cassidy is looking at to provide that scoring. McAvoy, sure. Krug, definitely. But not Grzelcyk. Not usually.
"It was fun to watch," Krug said. "I've been one of [Grzelcyk's] biggest fans since he came in the League and we joke about it all the time. We have a couple guys under 5-10 winning games in the National Hockey League and three D under 6-foot. We're causing havoc and doing the job. It's a lot of fun to watch him and when he's skating, there's no one that can skate like him and break out pucks."
All of which he practiced on the very ice he starred on on Sunday.
It was there that he pushed around a crate at 2 years old. It was there that he scored the overtime winner to hand Boston University the championship in the 2015 Beanpot, the annual city tournament between BU, Boston College, Harvard and Northeastern.
It was there that dreamed big and, on Sunday, turned a few of those dreams into reality.
"The Mayor of Charlestown, sitting next to me," Krug said, as he sat with Grzelcyk at the podium after the game, when asked about what it meant for the local products -- Grzelcyk, Coyle, Walpole, Massachusetts, product Chris Wagner and Johnston, Rhode Island, native Noel Acciari -- to be doing this, for the Bruins.
"That's important to our team," Krug said. "We have guys that take a lot of pride putting the sweater on, with the spoked-B. I think no one takes it for granted, that's for sure, as a whole, as a group. We're very prideful. But when you have local guys coming and doing it, having the success that they've had, it's a special feeling for them, I'm sure. And we all get a little bit of energy off it."
They did in Game 2, as Grzelcyk got knocked down and got up, as he proceeded then to knock down the Hurricanes in turn -- all in a place that could be considered his home, his rink, his place.
"Obviously," Grzelcyk said, "it's really special right now."
Video: CAR@BOS, Gm2: Grzelcyk speaks following Game 2 win
Listen: New episode of NHL Fantasy on Ice podcast