"We had chances in the game, some hard chances. In the third period we had a lot of powerplays but we just ran out of time," Sidney Crosby, a Canada superstar, said.
"Ryan Miller was really solid and made some big saves. Sometimes you run into a hot goalie but we had some bad luck sometimes."
Dany Heatley and Eric Staal scored for Canada, who suffered their first loss of the tournament and now have to play in the eight-team qualifying round on Tuesday.
"I hate to say it but I think we just need to play more games," Martin Brodeur, Canada's goalie, said. "There's things we need to work on, and hopefully that extra game will give us just that."
Like separate games
It looked like two separate games as the Canadians came charging out of the gate, outshooting the US 19-6 in the first period, but they could not get the puck past Miller who was superb in goal.
Canada outshot the Americans 45-23 overall.
"You've got Ryan Miller in net. I'll take a one-goal lead with this group and Ryan Miller in net any day," Jack Johnson, defenceman, said.
A goal by Dustin Brown, forward, late in the second period to make it 3-2, seemed to give the Americans a boost in confidence which they carried over into the third.
After Brown's goal, the Americans started to skate with the Canadians, playing like they did when they routed the Norwegians 6-1 in their previous game.
Brodeur looked shaky for Canada as he seemed to overhandle the puck several times and had trouble seeing shots through players' legs and sticks.
He got unnerved on Bobby Ryan's second period goal after David Backes, American forward, bumped into him the crease.
Crosby took a pass from Rick Nash and scored with just over three minutes left to pull Canada to within a goal, 4-3.
The Canadians then buzzed the American goal in the final moments but failed to get the equaliser.