"The Last Exorcism" tops weekend box office

The fright flick "The Last Exorcism" and the heist thriller "Takers" are in a photo finish for the top spot at the weekend box office.

According to studio estimates Sunday, "The Last Exorcism" had a thin lead with a $21.3 million debut, closely followed by "Takers" with a $21 million opening. They were close enough that rankings could change after final numbers are released Monday.

After two weekends in the No. 1 spot, the action romp "The Expendables" slipped to third place with $9.5 million, raising its total to $82 million.

Playing in narrower release, a 3-D special edition of "Avatar" pulled in $4 million, lifting the sci-fi sensation's domestic total to $753.8 million. The new version adds nine minutes of footage.