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The thriller Unknown relegated I Am Number Four to No. 2 at the box office, according to preliminary President's Day weekend figures from Box Office Mojo.

Unknown, which stars Liam Neeson and Mad Men's January Jones, grossed an estimated $21.7 million in its debut weekend. The teen science fiction film followed with $19.5 million in its opening weekend.

Adam Sandler's Just Go With It edges out Justin Bieber at the box office

Disney's animated Gnomeo and Juliet came in third with $19.4 million, while the Adam Sandler-Jennifer Aniston romantic comedy Just Go With It brought in $18.2 in its second weekend.

The Roommate moves into No. 1 spot at box office

Another new entry, Big Mommas: Like Father Like Son, made $17 million.

Justin Bieber: Never Say Never was No. 6 for the weekend, grossing $13.6 million. Oscar front-runner The King's Speech followed in seventh place, with $6.6 million — bringing its total to $103.3 million.

Rounding out the top 10: The Roommate (No. 8, $4.1 million), The Eagle (No.9, $3.6 million) and No Strings Attached (No. 10, $3.1 million).