The movie cost more than $100m (£70m) to make
Superhero film Watchmen has stormed to the top of the North American box office in its opening weekend.
The comic book adaptation about a team of retired, flawed superheroes took $55.7m (£39.8m) - the biggest opening weekend of 2009 so far.
However it fell short of the $60m-plus (£42.8m) range expected by Warner Bros.
With no other new releases to compete against, it easily surpassed last week's number one, Tyler Perry's Madea Goes to Jail, which took $8.8m (£6.3m).
Dan Fellman, president of domestic theatrical distribution at Warner Bros, said the film's 161-minute running time inevitably affected business, restricting cinemas to one main evening screening.
Male moviegoers accounted for about two-thirds of the audience, with the "sweet spot" aged between 17 and 35, Fellman said. Many Watchmen enthusiasts also raced to Imax cinemas to see the film on the bigger screens.
US BOX OFFICE
1. Watchmen - $55.7m
2. Madea Goes To Jail - $8.8m
3. Taken - $7.5m
4. Slumdog Millionaire - $6.9m
5. Paul Blart: Mall Cop - $4.1m
6. He's Just Not That Into You - $4m
7. Coraline $3.3m
8. Confessions of a Shopaholic - $3.1m
9. Jonas Brothers: The 3D Concert Experience - $2.8m
10. Fired Up - $2.6m
Source: Media By Numbers
Greg Foster, chairman and president of Imax Filmed Entertainment, said the movie sold out on all 124 Imax screens it was playing on during the weekend and was the second largest opening in the company's history behind 2008's The Dark Knight.
Fans of the comic book series by writer Alan Moore and illustrator Dave Gibbons waited two decades for the film to come to the big-screen.
The anticipation was complicated last year when Warner Bros and 20th Century Fox fought over who owned rights to the movie.
The studios eventually settled in January, keeping the 6 March opening intact.
Elsewhere on the box office chart, Liam Neeson thriller Taken rose one place to number three on the chart bringing its six week total to $118m (£84.7m).
The biggest casualty in the top 10 was Jonas Brothers: The 3D Concert Experience, which fell from number two to nine.