Ben Affleck, left, and Justin Timberlake star in “Runner Runner.” (Scott Garfield/Copyright: Twentieth Century Fox Film Corporation)

Justin Timberlake and Ben Affleck have Las Vegas on edge.

They are the stars of a new film about the murky world of unauthorized online poker that could cast an unwelcome spotlight on a fledgling legal market that Sin City’s biggest players are betting on.

Timberlake and Affleck are set to walk the red carpet with other celebrities at Caesars Palace next month for the premiere of Twenty-First Century Fox’s “Runner, Runner.”

In the movie, Affleck plays an online gambling tycoon in Costa Rica confronted by Timberlake, a graduate student who believes he’s been swindled by the gambling site.

It is a departure from the run of films like the “Hangover” series and “Ocean’s 11” that glamorized casinos and the Las Vegas Strip.

“People very well could get the wrong idea,” said John Pappas, executive director of the Poker Players Alliance. “Not all offshore operators are unregulated bad guys. This is a dramatization, let’s be clear about that. It shows what could be happening in a worst-case scenario.”

Industry groups such as the American Gaming Association are preparing advertising and discussion screenings around the film’s release, to draw a distinction between its portrayal of the seedy trappings of global online poker and a federally regulated market they’re trying to plug.

A legal, well-supervised market protects against fraud and cheating and increases revenue, its proponents argue.

Vegas’s biggest players see online poker as a new market that can offset slowing growth from table-gambling on the Strip. It is a market expected to grow by more than $10 billion in coming years from about $4 billion that’s being bet through unauthorized sites as of 2011.

A few states have already begun legalizing Web poker, eyeing the tax revenue the games will bring.

Yet the Justice Department’s 2011 crackdown on foreign operators has left a sour taste in the mouths of many.

“The specifics of the film are not what we’re associating ourselves with,” said Joe Versaci, chief marketing officer for Station Casino Inc.’s Ultimate Gaming, which, in Nevada last April, became the first company to take online bets in the United States. It has applied for a Web gaming license in New Jersey, which is expected to launch online betting in November.

The problem for most Vegas operators is that they have teamed up with more-experienced poker-game operators overseas, which the film portrays in a sordid light. Caesars tied up with London-listed 888 Holdings, and MGM Resorts has aligned with Bwin.Party Digital Entertainment, to name a couple.

Offshore poker Web sites such as PokerStars were the forces behind the last online poker boom, starting around 2003. That all changed on April 15, 2011, known in the industry as “Black Friday,” when the Justice Department charged the founders of these sites with bank fraud, money laundering and illegal gambling.

The sites were closed to U.S. players, but now tax-hungry states, including Nevada, New Jersey and Delaware, are passing online gambling laws, reopening the market.

The American Gaming Association, the trade group for the world’s big casinos, has decided to spin the movie as part of its lobbying platform for expanded regulation of online gambling.

AGA President Geoff Freeman, in an e-mail sent to its board last week and obtained by Reuters, plans to argue that the film underscores the risks of a poorly regulated market.

Both the AGA and the Poker Players Alliance have long advocated a federal online gambling bill that would allow a larger, more uniform market, but efforts in Congress have stalled. Two bills have recently been introduced in Congress as states move to pass their own laws.

Twenty-First Century Fox had no comment on the AGA letter.

“Hollywood has a way of glamorizing everything up to and including vampires. This is a movie that highlights a part of the Internet that has real downside unless governments act,” said MGM spokesman Alan Feldman.

Caesars thought long and hard about the risk of being associated with the film. The company plans to soon go live with an online poker site in Nevada and is awaiting approval in New Jersey.

“There was a lot of discussion of whether we wanted to be part of ‘Runner, Runner,’ but we decided we could draw a nice distinction between the illegal, unregulated world and the regulated market we are advocating,” said Tariq Shaukat, chief marketing officer for Caesars.

It was also hard to turn away a chance to have Timberlake on a red carpet, he added.

— Reuters