Ashton Kutcher has scored a rare prize at the top of the US box office - he features in the top two films.

The actor voices a one-antlered mule deer in family cartoon comedy Open Season, which has debuted in first place ahead of his portrayal of a cocky coastguard in Kevin Costner's new action film The Guardian.

The animated film, which also features the voices of Debra Messing, Martin Lawrence and Billy Connolly, enjoyed a first weekend take of $23 million, while The Guardian debuted with $17.7 million.

Last week's box office top film, Jackass: Number Two, dropped to number three, while Billy Bob Thornton comedy School For Scoundrels was a disappointing fourth with a debut of $9.1 million.