Even Justin Timberlake and Ben Affleck, two of Hollywood’s heavyweight hunks, couldn’t keep “Runner Runner’ from stumbling out of the box-office blocks this weekend.

The R-rated thriller took in just $7.6 million over the course of its three-day U.S. debut, well under analysts’ projections, which were low to begin with.

“That’s not what you’d expect from one of the world’s biggest pop stars and the next Batman,” said Exhibitor Relations vice-president and senior analyst Jeff Bock.

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Timberlake last week was heading up the music charts with his new album “The 20/20 Experience 2 of 2,” and Oscar winner Affleck was recently chosen to play the Caped Crusader in Zach Snyder’s upcoming “Man of Steel” remake.

It’s quite a comedown for Affleck, who was last seen in “To the Wonder” earlier this year and before that “Argo,” last year’s box-office hit and Best Picture Oscar winner that he directed and starred in.

For Timberlake, it’s another off effort in an uneven film career that’s trending down of late.

The critics weren’t keen on the $30 million New Regency production – it has a terrible 8 percent positive rating on Rotten Tomatoes – and audiences didn’t like it much either, giving it just a “C” CinemaScore.

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Brad Furman (“The Lincoln Lawyer”) directed “Runner Runner,” in which Timberlake plays a college student who is cheated out of his tuition money playing online poker and confronts the offshore entrepreneur (Affleck) behind it. He becomes the kingpin’s right-hand man and winds up in a tight spot when the FBI wants to use him to bring the operation down. Leonardo DiCaprio is a producer, and Gemma Arterton and Anthony Mackie co-star.

Offering some solace for distributor Fox were the overseas grosses. With this weekend’s foreign receipts added in, “Runner Runner” has taken in $23.5 million from overseas.

In part because of his music roots, Timberlake’s films have recently performed decently overseas even when disappointing domestically.

His two most recent movies, 2011’s “In Time” and last year’s Clint Eastwood baseball movie “Trouble With the Curve,’ both under-performed in the U.S. “In Time” took in $135 million from overseas, however.

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Early on in his film career, Timberlake bucked his squeaky-clean ”N Sync image with roles in gritty indie films like “Alpha Dog” and “Southland Tales.” He broke out with his portrayal of Napster co-founder and Facebook mentor Sean Parker in 2010’s “The Social Network.” And in 2011, he showed his comedy chops in “Bad Teacher” and “Friends with Benefits,” which was well-reviewed and lucrative, taking in $150 million worldwide for Sony Screen Gems.

With the crummy reviews and a marketing campaign that failed to ignite much buzz, “Runner Runner” was always in for a tough ride. And when it bumped up against the Sandra Bullock-George Clooney space saga “Gravity,” which posted an October record $55 million debut this weekend, its fate was sealed.