Team Canada survived a second period run by the Americans and will now have the chance to win a gold medal for the second time in as many years.
Ryan Ellis scored the winner 1:34 into the third period and Canada defeated the United States 4-3 on Saturday in the semifinals of the World Championship.
Team USA tallied three times in the first 8:25 of the middle period after falling behind 2-0 in the first 20 minutes. Auston Matthews and David Warsofsky netted the first two goals for the U.S., while Avalanche prospect JT Compher helped set up Tyler Motte's go-ahead marker.
Compher played 13:13 and had one shot and a plus-1 rating while centering the line with Motte and Larkin.
Derick Brassard evened the contest for the Canadians at 3-3 with a power-play tally at 15:30 of the second period.
The Americans had a strong push in the third period after Ellis' goal but were unable to notch the equalizer at the Ice Palace in Moscow, Russia. They outshot the Canadians 11-4 in the frame and 33-27 overall.
"We made some mistakes tonight that almost cost us, but we were able to outlast them," said Avs forward Matt Duchene of Canada. "It's never easy. We sat back at times tonight, but fortunately we were able to outlast them."
Duchene finished with a plus-2 rating and won 60 percent of his faceoffs (3-for-5) in 17:34 of ice time. He helped set up Canada's second goal with 1:58 left in the first period, as his leading pass led to an odd-man rush the other way and Brad Marchand's tough-angle tally.
Goaltender Calvin Pickard did not play in the game for Canada.
Team Canada faces Finland in the gold medal game on Sunday at 7:15 a.m. MT. The two teams previously met on the last day of the preliminary round on Tuesday, with Finland winning 4-0.
FINLAND (3) VS. RUSSIA (1)
Finland is one win away from history, while the host country will have to settle for playing for a consolation bronze medal.
Sebastian Aho scored twice and Jussi Jokinen also tallied as Team Finland beat Russia 3-1 on Saturday at the Ice Palace in Moscow to advance to the World Championship final.
With a win on Sunday against Canada—the defending champions—Finland would become the first nation to win the IIHF's Under-18, World Junior Under-20 and World Championship in the same calendar year.
Sergei Shirokov gave Russia an early lead just 2:52 into the contest, but that would be the only goal the home team would score as Finland beat goalie Sergei Bobrovsky three times in the second period.
The Finns have yet to lose in the tournament. The squad won all seven contests in the preliminary round to take the top seed in Group A and then defeated Denmark 5-1 in the quarterfinals on Thursday.
Avalanche prospect Mikko Rantanen was a fourth line forward for Finland and had a minus-1 rating and two shots in 4:51 of ice time.
Russia will take on the United States in the bronze medal game on Sunday at 7:15 a.m. MT.