The Sam Raimi-produced The Possession could score one of the top Labor Day weekend openings of all time if traffic holds.
Lionsgate's horror pic -- directed by Ole Bornedal and inspired by films including The Exorcist -- topped the Friday chart, grossing $6.1 million for a possible four-day cume of $20 million.
Halloween is the top Labor Day opener of all time, opening to $30.6 million in 2007; Transporter 2 is No. 2, grossing $20.1 million in 2005.
Possession stars Kyra Sedgwick, Jeffrey Dean Morgan and Natasha Calis.
Overall box office revenues will still be down from last year because of the The Help, which turned into a box office hit after opening in mid-August 2011.
John Hillcoat's Prohibition-era drama Lawless, which opened Wednesday, is holding safely at No. 2, grossing $2.8 million on Friday for a projected four-day gross of $12.4 million. That would put the film's six-day cume at between $14 million and $15 million.
Lawless, from The Weinstein Co., stars Tom Hardy, Shia LaBeouf, Jessica Chastain, Jason Clarke, Guy Pearce and Mia Wasikowska.
Anti-Barack Obama documentary 2016: Obama's America continues to do strong business and should finish the Labor Day holiday with a domestic total of nearly $20 million.
Kids entry The Oogieloves in the Big Balloon Adventure also opened Wednesday but to continues to fare dismally, coming in No. 24 on Friday with a gross under $100,000 from 2,160 theaters. The pic's six-day opening may only be $1.3 million, marking one of the worst openings of all time for a film playing in that number of theaters.
Summer hits The Avengers, Brave and Madagascar 3: Europe's Most Wanted are all upping their theater counts this weekend, hoping for a final burst of summer business.