Sweden got an early lead through Detroit Red Wings forward Johan Franzen, who swept home a rebound past Czech goalie Jakub Stepanek after 2:42.
Defender Niklas Kronwall added his goal just 50sec into the second, beating Stepanek with a sharp-angled shot to lift Sweden 2-0 up.
Jakub Petruzalek reduced arrears 3:44 into the third period, sweeping the puck in after Sweden team goalie Viktor Fasth schoolboy's mistake, but Joel Lundqvist dashed Czech hopes with his insurance goal at 50:24.
Czech coach Aloiz Hadamczik subtituted Stepanek for the sixth field player in the late stages but only to allow Niklas Persson to finalise the scoring with his empty-netter with 1:56 to go.
The United States, bidding for their first world title since 1960, meanwhile snatched a hard-fought 5-4 overtime win against Canada.
US skipper Jack Johnson was the hero scoring the sudden-death winner -- his second powerplay goal of the match -- to secure his side's leading position in their preliminary group standings.
Winnipeg Jets' striker Jim Slater got the US off to a flying start just 1:10 into the match with a wristed puck home through the traffic.
Canada replied positively striking back twice through New York Islanders' forward John Tavares and Carolina Hurricanes' Jeff Skinner for a 2-1 lead before Johnson levelled at 2-2 at 33:54.
In the third period the opponents traded goals twice again as Patrick Dwyer and Nate Thompson scored for Americans, while Evander Kane and Duncan Keith were on target for Canada.
The United States, who started the overtime on powerplay after Tavares was sinbinned for time wasting, needed just 1:47 to score the winning goal through
Johnson, who beat Canada's goalie Cam Ward with a mid-range wrist shot.
"Canada is always a formidable opponent," said US team manager Scott Gordon.
"Look at their roster, there are few guys that scored less than 20 goals in the (regular NHL) season.
"The key for us was that we played a complete game in all three zones. And our powerplay was huge tonight."