Ben Affleck started his day with critical raves for his movie "Argo," but he's still concerned about how it will perform at the box office.

"This is a hard movie to sell," Affleck told TheWrap on Friday. "I think this movie has to hold to be successful. If it doesn’t, I won’t be happy. It needs good word of mouth. If it doesn’t happen I’ll be disappointed."

Affleck has a lot invested in the movie about the 1979 Iranian hostage crisis. 

At the beginning of the week, Warner Bros. downgraded its projections following weaker-than-expected tracking for the film, which opens on 3,232 screens. Studio executives are hoping to open above $15 million, and industry analysts’ projections range from $16 million to $24 million.

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"If we could get over $15 million, that would be great," Affleck said. "And a bigger indicator will be how we hold next week."

In the film, he plays real-life CIA operative Tony Mendez, who plotted a daring rescue plan for six Americans who slipped out the compound and hid at the Canadian ambassador's residence in Tehran. Mendez and the CIA concocted a Hollywood cover story to smuggle the Americans out of the country.

"Argo" was originally scheduled for release in September but moved to Oct. 12 after Warner Brothers changed the release date of Ruben Fleischer's "Gangster Squad," starring Ryan Gosling, Nick Nolte and Josh Brolin.

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One individual with knowledge of the situation told TheWrap that Affleck had sought a Christmas release -- something he denies.

"Today I thought was pretty good date for us," he said. "I would have been terrified to have my movie open at Christmas. We would have gotten buried."

But he still has reason to be concerned.

"Argo" has built up a huge amount of pre-release Oscar buzz following the film’s screening in Telluride and Toronto. And the film needs to make at least $25 million this weekend to keep the studio happy, a person familiar with the situation told TheWrap.

"Argo" opens against five other films this weekend, including "Seven Psychopaths,” “Sinister,” “Atlas Shrugged Part 2” and “Here Comes the Boom,” in addition to “Taken 2” and “Hotel Transylvania.”

It's a situation similar to the opening weekend competition he faced with 2007's "Gone Baby Gone," which he co-wrote and directed. That film, which brought star Amy Ryan an Academy Award nomination, faced six other films at the box office when it opened.

"I don’t see this as a big weekend movie. I see it as one to come out and play," he said of "Argo." "If it’s gonna be successful, it needs to make a decent footprint, and hold and play over time -- that was the strategy with this movie. We seem to be following through.

"This movie has its audience; it’s about getting them to come over time."

Liza Foreman contributed to this report.