Card-counting thriller 21 has debuted at the top of the North American box office after making distributor Sony $23.7 million (£11.9 million).

The Kevin Spacey-starring drama, which also features Jim Sturgess and Kate Bosworth, is based on the true story of Harvard maths students turning the tables on Las Vegas casinos.

21 pushed last week's number one Horton Hears a Who! off the number one spot.

Nevertheless, the CGI adaptation of Dr Seuss' book of the same name, featuring Jim Carrey as the eponymous Horton, is the first film to earn more than $100 million (£50.3 million) in 2008 after reaching $117.3 million (£59 million) of ticket sales.

Opening in third place was Superhero Movie, although its box office return of $9.5 million (£4.8 million) put it far behind other genre spoofs Meet the Spartans and Epic Movie.

Iraq war drama Stop-Loss, starring Ryan Phillippe, was the top ten's only other new entry at eight, while David Schwimmer's directorial debut – Run, Fat Boy, Run – disappointed in 12th.

The comedy was a minor hit when released in the UK last autumn but failed to impress US cinemagoers, despite star Simon Pegg's stateside popularity from Hot Fuzz and Shaun of the Dead.

North American box office

1 21 (new entry)
2 Horton Hears a Who! (1)
3 Superhero Movie (new entry)
4 Tyler Perry’s Meet The Browns (2)
5 Drillbit Taylor (4)
6 Shutter (3)
7 10,000 BC (5)
8 Stop-Loss (new entry)
9 College Road Trip (7)
10 The Bank Job (8)

31/03/2008 11:15:46