The United States defeated Russia in a shoot-out to win a much-hyped group-stage ice hockey clash at Sochi 2014.
TJ Oshie scored the winner at the eighth time of asking as a prolonged shoot-out capped one of the great Olympic encounters between the two.
The teams had finished regulation play level at 2-2, Russia having a third goal controversially wiped out.
President Vladimir Putin looked on as Oshie's goal prompted US celebrations after Ilya Kovalchuk had missed.
"The US team is a good team, a good test for us," said Russia captain Pavel Datsyuk. "I think our team played great tonight, but our result was not good.
"It's one game. We need to play at the same level every time and we'll be OK."
US goaltender Jonathan Quick denied Kovalchuk after seven shoot-out attempts had failed to separate the two fierce rivals.
The final score was 3-2 to the US, with Oshie's game-winning penalty counting as the decisive goal.
Datsyuk had put an initially dominant Russia ahead, but Cam Fowler and Joe Pavelski scored for the US before Datsyuk's second tied the game.
However, two of Datsyuk's three appearances in the shoot-out ended in failure as the US earned a win that while not as momentous as 1980's "miracle on ice" - in which an amateur US side beat the Soviet Union - was every bit as gripping to watch.
The hosts are under immense pressure to win Olympic gold in Sochi. No Russian team has won the title since the break-up of the Soviet Union (though some Russians took part in the "Unified Team", representing six former Soviet republics, which won gold in 1992). They are now second in Group A after two games with the US leading.
"Everything is OK, nothing terrible has happened," said Kovalchuk. "We played good and showed our character by equalising the game at the end and now we will be getting ready for the future.
"I hope we will get a chance to play against them again."
The US, meanwhile, are out to improve on the silver medal they won at Vancouver 2010, where hosts Canada took gold.
"It was unbelievable," said Fowler. "You're not going to see something like that ever again. To see Oshie step up like that, time after time, with the game on the line and to see 'Quickie' make the saves that he did.
"Those are really big plays and we needed them."
Fyodor Tyutin thought he had scored the game-winning goal for Russia late in the third period, but officials cancelled out the goal on video review as the US net had been fractionally off its moorings.