Minka Kelly and Leighton Meester's 'The Roommate' tops weekend box office - SEE VIDEO

Minka Kelly and Leighton Meester's thriller "The Roommate" bested "Sanctum" this weekend in the U.S. box office rankings.

"The Roommate", released by Sony, grossed $15.6 million in its opening week.

The dark thriller tells follows the story of Sara Matthews (Minka Kelly) the roommate of Rebecca (Leighton Meester). Kelly's character becomes obsessed with her new college roommate and eventually turns into a psycho killer.

James Cameron's 3D thriller "The Sanctum", from Universal, came in second grossing $9.2 million. While the Ashton Kutcher, Natalie Portman comedy from Paramount, "No Strings Attached" came in third with $8.4 million.