Sens captain Daniel Alfredsson, shown during pre-game introductions prior to Sweden's quarter-final against the Czech Republic, called the loss one of the toughest of his career (Photo by Andre Ringuette/HHOF-IIHF Images).

Milan Michalek broke the hearts of his Senators teammates.

The Ottawa forward scored with just 29 seconds left in regulation as the Czech Republic stunned Sweden 4-3 to close out a wild day of quarter-final action at the 2012 IIHF world hockey championship.

Sweden, which was playing its final game of the world tournament on home ice at the Ericsson Globe Arena in Stockholm, had rallied from a 3-1 deficit on goals by Henrik Zetterberg and Jonathan Ericsson of the Detroit Red Wings. But Michalek dashed the gold medal hopes of the Tre Kronor, whose roster included captain Daniel Alfredsson, defenceman Erik Karlsson and forward Jakob Silfverberg of the Senators.

The 39-year-old Alfredsson, playing in his seventh world championship, was hopeful of striking gold after collecting two silver and two bronze medals in previous tournament appearances. Though he has yet to decide whether he'll return to the Senators to play out the final year of his contract in Ottawa, Alfredsson might well have suited up for his country for the last time, making this loss all the more tougher to take.

"It's one of the (most difficult) losses I've experienced," Alfredsson told Sverige Radio after the game. "Why? If this is the end of my career, it may well be the last thing I do on the ice. It would be hard (to end it that way)."

The Swedes led only once in the quarter-final matchup, when Loui Eriksson of the Dallas Stars opened the game's scoring at the 7:10 mark of the first period. However, the Czechs seized control when former NHLers Petr Nedved and Jiri Novotny scored later in the opening frame. Michalek drew an assist on the latter goal.

Martin Erat of the Nashville Predators pushed the Czech lead to 3-1 midway through the second period, but Zetterberg closed the gap back to one by hitting the scoresheet with just 45 seconds left in the frame. Then Ericsson tied it a mere 45 seconds into the third.

The game appeared headed to overtime until Michalek's dramatic game-winner. The Senators winger stripped the puck from Swedish blueliner Niklas Kronwall of the Red Wings, drove the net and buried a high shot past goaltender Viktor Fasth to silence the Globe crowd.

"I think it was a great forecheck," Michalek told IIHF.com. "I got the puck and it was 2-on-1, and I knew the goalie was going to go down. The defenceman took away the pass, so I shot glove side and it went in. I’m happy."

Alfredsson just missed tying the game in the dying seconds, with his point shot just zipping wide of the net.

It was also a tense quarter-final ride for the tournament's other co-host. But Finland rallied past the United States 3-2 at the Hartwall Arena in Helsinki, getting the winner from Jesse Joensuu with just nine seconds to play.

Finland advances to Saturday's semifinals against Russia (7:30 a.m., TSN), which ousted Norway 5-2 in the quarter-finals. Meanwhile, the Czechs will face arch-rival Slovakia (11:30 a.m., TSN), which shocked Canada 4-3 in the first quarter-final of the day.

"We speak the same language, and we have lots of friends on their team," Michalek said of the matchup with the Slovaks. "It’s a semifinal, so it’s going to be a great game. They beat Team Canada and that’s one of the best teams here. Their goalie is playing well. It’ll be a tough game."

The gold/silver and bronze medal games are set for Sunday in Helsinki.