"There's one more chance for us to beat Finland," Canada forward Ryan O'Reilly said. "It's a golden game, everything will be different. It's our chance to prove we are a team."
The U.S. will face Russia in the bronze-medal game (9:15 a.m. ET).
"It was tough, obviously," U.S. forward Auston Matthews said. "Canada played very well, they took a lot of bounces, capitalized on some opportunities. Tomorrow against Russia, the building will be very loud. We are focusing on the bronze-medal game."
Finland defeated Canada 4-0 in Group B preliminary play Tuesday.
"They played well against us last game," Ellis said. "I think we're comfortable with shooting and getting the job done, but we're going to have to be better than we were in that 4-0 game."
Matthews, No. 1 on NHL Central Scouting's final ranking of international skaters eligible for the 2016 NHL Draft, scored his sixth goal of the tournament, and Keith Kinkaid (New Jersey Devils) made 23 saves for the United States.
After Canada took an early two-goal lead, the United States struck for three straight second-period goals. Matthews cut Canada's lead to 2-1 on the power play at 1:14, and David Warsofsky (Devils) knotted the score at 3:57.
"We responded very well in the second period," U.S. forward Dylan Larkin said. "Unfortunately we couldn't hold it. Tomorrow we have to be disciplined, don't lose a puck, make smart decisions. I'm excited to play against [Red Wings teammate Pavel] Datsyuk tomorrow. It's going to be a learning lesson."
Tyler Motte (Chicago Blackhawks) gave the United States a 3-2 lead at 8:25 of the second, but a power-play goal by Canada's Derick Brassard (New York Rangers) tied the game 3-3.
Brendan Gallagher (Montreal Canadiens) opened the scoring for Canada at 8:59 of the first period when he scored on a rebound of a Sam Reinhart (Buffalo Sabres) sharp-angle shot and put it past Kinkaid. Brad Marchand (Boston Bruins) scored his fourth goal of the tournament at 18:02 to make it 2-0.
Finland 3, Russia 1
Carolina Hurricanes prospect Sebastian Aho scored two power-play goals to lead Finland to a comeback victory in the semifinal at Ice Palace.
Undefeated Finland is one win away from completing the unprecedented feat of winning the World Junior Championship, the World Championship and Under-18 World Championship in the same year.
Trailing 1-0 after the first period, Finland scored three goals in the second. Aho's first power-play goal came at 5:34, assisted by Mikael Granlund (Minnesota Wild) and Esa Lindell (Dallas Stars). Finland took a 2-1 lead at 15:50 on a goal by Jussi Jokinen (Florida Panthers) and made it 3-1 on Aho's second power-play goal less than three minutes later.
Patrik Laine, No. 2 on NHL Central Scouting's final ranking of international skaters eligible for the 2016 NHL Draft, had one assist in 17:41 of ice time for Finland.
