(NEW YORK) -- The Liam Neeson stolen identity drama Unknown was a surprise box office winner this past weekend, taking in $21.7 million.
Pundits expected the weekend to see the Martin Lawrence comedy Big Mommas: Like Father, Like Son battle it out with the teen sci-fi thriller I Am Number Four. Instead, the latter debuted in second, with $19.5 million, while Big Mommas managed $17 million, good for a fifth-place debut.
Last week's number-one, the Jennifer Aniston-Adam Sandler romantic comedy Just Go with It, dropped to fourth place, while teen pop star Justin Bieber's docu-biography Justin Bieber: Never Say Never, dropped four spots to sixth.
Here are the top 10 movies from Friday through Sunday, with estimated ticket sales:
1. Unknown, $21.77 million.
2. I Am Number Four, $19.50 million.
3. Gnomeo and Juliet, $19.40 million.
4. Just Go with It, $18.20 million.
5. Big Mommas: Like Father, Like Son, $17.00 million.
6. Justin Bieber: Never Say Never, $13.60 million.
7. The King's Speech, $6.57 million.
8. The Roommate, $4.1 million.
9. The Eagle, $3.56 million.
10. No Strings Attached, $3.12 million.
Copyright 2011 ABC News Radio