Modesty becomes the man.
Among the 19,000-plus wedged into the Scotiabank Saddledome stands that erupted along with the red light behind Colorado goaltender Phillip Grubauer were Mangiapane's parents, Patricia and Peter, in town for the first two post-season dates.
"Very exciting," said dad. "The atmosphere in the arena was just … unbelievable. So we were already pumped up. First period, no goals, then he puts one in in the second.
"Very emotional. Very emotional.
"Just relief. He's a good player, but to get the first goal in his first playoff game? Oh my god. The monkey's off his back, right? When he first got called up it took him 20-odd games to score his first goal.
"So that pressure is off now."
Back home in Ontario, Patricia revealed, folks were burning the past-midnight oil Thursday.
"In the sleepy town of Bolton" - pop. 26,000 - "people are walking around with bags underneath their eyes,'' she said.
"These games are killers for us out there, at 1:30 (a.m.).
"Everyone's a hockey fan now. Even my husband's parents, they're up at 1 o'clock, 2 o'clock, to cheer them on. Nice that everybody's getting into it."
The Mangiapane strike proved decisive, allowing the Flames to exhale and begin to re-establish rhythm lost by penalty issues.
"I think Hathaway was more excited than Andrew, I think," laughed Patricia. "But that's how it is in playoffs.
"They truly don't care how it goes in or who puts it in as long long as it's in.
"It was a relief, that goal. You could tell. They could all take a deep breath and start to play hockey."
The lustre, the quality, of the finish, too, seemed to revitalize the homestanding Flames.
This was the kind of goal a guy can call up on YouTube 30 years from now to show the kids and maybe grandkids just how much moxie the old man had back in the day.
"I haven't seen the replay," confessed Ryan, "but from my first-hand perspective we rimmed it around and he did a good job picking it off the wall. I was kinda net-front, trying to pick off the wall. I was trying to be net-front, picking off the D-man.
"He showed good patience.
"Mang is a skilled player. He makes plays like that whether it's the Stanley Cup Playoffs or whatever. I'm not surprised.
"That first goal is huge, for sure. Especially Game 1 of a playoff series, teams are kinda feeling each other out a little bit. The home crowd, you want to get them energized even more than then already are.
"The first goal obviously did that."
Fellow 'DAG Line' stablemate and longtime pal Garnet Hathaway was first to the scene, mobbing his teammate and offering a few jabs to the ribs in a flash of elation both will not soon forget.