"Swingers" co-stars Vince Vaughn and Jon Favreau buddied up for the weekend's top movie as "Couples Retreat" debuted with $35.3 million, while the micro-budgeted fright flick "Paranormal Activity" leaped into the top 10.

Shot for a reported $15,000, "Paranormal Activity" came in at No. 5 with $7.1 million as distributor Paramount expanded it into daylong release after two weeks of midnight-only screenings.

"Paranormal Activity" played in narrow release of just 160 cinemas, a fraction of the theater count for other top movies. It averaged a whopping $44,163 a theater, compared with $11,780 in 3,000 theaters for "Couples Retreat."

"You almost do a double take when you look at that theater count for a movie in the top five," said Paul Dergarabedian, box-office analyst for Hollywood.com. "That's amazing. That's unprecedented."

"Couples Retreat" exceeded expectations for distributor Universal Pictures, which had hoped the movie would top the $20 million range. The solid opening came just days after Universal replaced top managers Marc Shmuger and David Linde with Adam Fogelson and Donna Langley, who were promoted from other jobs within the studio.

The management shake-up followed a summer of slim pickings at the box office for Universal, which released the Will Ferrell dud "Land of the Lost" and such commercial underachievers as Adam Sandler's "Funny People" and Jennifer Aniston's "Love Happens."

"I feel pretty good today. Happy to have a hit," said Nikki Rocco, head of distribution for Universal. "It happened at the right time, because it did lift our spirits, having the summer we had."

Along with Vaughn and Favreau, whose collaborations include last year's holiday hit "Four Christmases," "Couples Retreat" features Jason Bateman, Kristin Davis, Kristen Stewart and Malin Akerman in a tale of friends at an island therapy resort.

"Paranormal Activity" was acquired by former Paramount partner DreamWorks at 2007's Slamdance Film Festival with the idea that writer-director Oren Peli would re-shoot it on a bigger budget.

But after audiences responded well to a test screening, Paramount decided to sneak "Paranormal Activity" out in a manner befitting its raw, independent roots. The studio began two weekends ago with midnight screenings in 13 cities, the movie building buzz online much as "The Blair Witch Project" did 10 years ago.

Like "Blair Witch," "Paranormal Activity" is fiction shot in documentary style as a young man tries to record strange doings and apparitions in the house he shares with his girlfriend.

Fans talked it up on Twitter and Facebook, while the movie expanded to more cities based on which markets received the most requests to see it on a Web site Paramount set up. This past weekend's 46 markets were heavy on big cities, but mid-sized cities such as Norfolk, Va., also made the cut as fans there voted to bring the movie.

"We all spend a lot of time talking about Facebook and Twitter and our ability to communicate. Here's a case where it allows people to rally around a movie they care about and for them to have a sense of participation, then tell other people, 'Hey, this is something you should see, too,"' said Rob Moore, Paramount vice chairman.

According to Paramount, "Paranormal Activity" had a record weekend for a movie playing in fewer than 200 theaters, surpassing the $3.7 million haul for "Platoon" in 174 theaters early in its run in 1987. Factoring in today's higher prices for movie tickets, which average nearly twice as much as in 1987, "Paranormal Activity" sold about the same number of tickets as "Platoon."

Including its take from midnight screenings the previous two weeks, "Paranormal Activity" has grossed $8.3 million. Paramount plans to expand it to several hundred more theaters next weekend, again adding new markets based on where it gets the most requests.

Sony's "Zombieland," the No. 1 movie the previous weekend, slipped to second place with $15 million, raising its total to $47.8 million.

In limited release, the acclaimed British drama "An Education" opened strongly with $162,381 in four theaters for an average of $40,595 a cinema. The film stars Carey Mulligan, Peter Sarsgaard and Alfred Molina in the story of a 1960s teen whose route to an Oxford education is sidetracked by an affair with an older man.

Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Hollywood.com. Final figures will be released Monday.

1. "Couples Retreat," $35.3 million.

2. "Zombieland," $15 million.

3. "Cloudy With a Chance of Meatballs," $12 million.

4. "Toy Story" and "Toy Story 2" in 3-D, $7.7 million.

5. "Paranormal Activity," $7.1 million.

6. "Surrogates," $4.1 million.

7. "The Invention of Lying," $3.4 million.

8. "Whip It," $2.8 million.

9. "Capitalism: A Love Story," $2.7 million.

10. "Fame," $2.6 million.