Russia was the defending champion in the Men's World Hockey Championship, had Alex Ovechkin on its side, and had never given up eight goals in the tournament.
Until Thursday. The U.S. beat the Russians 8-3 in Helsinki, avenging a 5-3 loss in the preliminary round.
The two catalysts for the offensive explosion were Paul Stastny with two goals and two assists and Craig Smith with five assists. John Gibson made 31 saves.
The U.S. led 2-1 after one period, 4-1 after two.
This is the first time since 2009 that the Americans have reached the semifinals in this tournament.
Their next game is against surprising Switzerland at noon on Saturday in Stockholm.
Ovechkin had a goal and an assist for Russia, both in the third period.
"We played a really good game and I'm proud of our team," said Joe Sacco, coach of the U.S. team.
"I thought our goaltender made a couple of big saves early to keep it scoreless and then we were able to get the lead and keep it.
"We scored timely goals today and got contributions from everyone up and down our lineup. We beat a very good hockey team and we're excited now to move over to Stockholm."
Switzerland placed 11th our of 12 teams in the World Championship a year ago. But now the Swiss are 8-0 in this tournament after beating the Czech Republic 2-1 in the quarterfinals. This is the first time they are in the semifinals since 1998.