The 17-year-old forward was promoted to the top forward line and scored a pretty goal in Canada's 4-1 win over Russia at the world junior hockey championship Monday.
The Canadians topped Pool B at 4-0, which means they get a bye to Thursday's semifinal. They await the winner of Wednesday's quarter-final between the Czech Republic and the United States.
Defending champion Sweden finished first in Pool A and awaits the winner of the quarter-final between Russia and Switzerland.
Drouin hadn't played or practised with captain Ryan Nugent-Hopkins or winger Mark Scheifele before Monday's game, but Canada's youngest player looked comfortable with linemates who would have played in the NHL this season if not for the lockout.
"I don't consider that a gamble when you're dealing with a player like Jonathan," Canadian head coach Steve Spott said. "Some players can handle that opportunity."
Dougie Hamilton and Scheifele scored power-play goals during a five-minute major to Russian forward Valeri Nichushkin, who was also given a game misconduct for checking Canadian defenceman Tyler Wotherspoon from behind in the first period.
The hit opened a cut on Wotherspoon's right cheek he'd sustained earlier in the game. The Surrey, B.C., defenceman left Canada's bench to get seven stitches in his cheek but returned for the second period.
Team captain Nugent-Hopkins assisted on all three of Canada's first three goals. Jonathan Huberdeau added an empty-net goal.
Malcolm Subban picked up his fourth win of the tournament in Canada's net with 21 saves.
Nikita Kucherov scored for Russia and goaltender Andrei Makarov of the Western Hockey League's Saskatoon Blades made 44 saves.
Spott wanted more speed on his top line to throw at the Russians when playing them even-strength, so he moved Drouin up from the second line of Ryan Strome and Brett Ritchie. Huberdeau re-joined Nugent-Hopkins and Scheifele when Canada went on the power-play.
Of the two underage players to make the Canadian team out of selection camp, Drouin was the surprise.
His Halifax Mooseheads teammate and linemate Nathan MacKinnon was seen to have the better chance at cracking a lineup of elite 19-year-olds because of the lockout.
Drouin had the hockey sense and speed, but there were concerns about his ability to compete physically against older and bigger players.
The five-foot-10, 185-pound winger scored a highlight reel goal in the second period Monday to put his country up 3-1.
Nugent-Hopkins dished him the puck low and Drouin whipped around the side of the net to tuck the puck between Makarov's pad and the post.
"He's so dynamic, he's so quick down low," Nugent-Hopkins said. "He's got good vision obviously so it's fun when you get a chance to play with a guy like that. He's handles himself really well as a 17-year-old in this tournament."
Central Scouting ranked Drouin second behind MacKinnon in their preliminary rankings of Quebec Major Junior Hockey League prospects.
"I don't think about my stats right now," Drouin said. "I'm here to win a gold medal."
The Huberdeau, Que., native was told by Spott in the morning he'd join Nugent-Hopkins and Scheifele in an important game for Canada.
"Maybe a little nervous to play with those guys," Drouin said. "They're great players. You've just got to find open space and they're going to find you pretty easy."
Canada had 13 forwards Monday for the first time in the tournament. Boone Jenner was assessed a three-game suspension on the eve of the tournament for his hit in a pre-tournament game. JC Lipon served a one-game suspension Sunday in the game against the U.S.
Jenner, a faceoff specialist and strong penalty killer, wore the black cape Canada's coaches award to the player they deem the most heroic in the game.
A full complement of forwards made Canada effective on the backcheck and gave the defence more support, according to Spott.
"Tonight, having those extra forwards, it allowed our defence to hold our gaps and we had great legs," Spott said. "We had really, really good legs. We got to loose pucks first."
The New Year's Eve game in Ufa was highly anticipated. The host country and Canada are tournament favourites and the 8,250-seat Ufa Arena was full for the game that determined first place in the pool.
"It was a game we all had marked on our schedule, the game against the Russians," Wotherspoon said. "The boys responded and came out great tonight."
The game also featured Nugent-Hopkins and Russian forward Nail Yakupov, who were the first overall selections of the last two NHL entry drafts by the Edmonton Oilers.
Nugent-Hopkins has already played a season in the NHL, while the lockout has prevented Yakupov from embarking on his rookie season with the Oilers. Canada's captain had more of an impact in Monday's game than his Russian counterpart.
Also on HuffPost