Boxoffice Pro is projecting "Joker" to make $103 million in its US opening.

That would be the biggest October opening of all time, beating the record set by "Venom."

"Of notable impact in recent days has been the film's hugely positive reception at Venice Film Festival and the ensuing wave of gushing critics' reviews," Shawn Robbins, the Boxoffice Pro chief analyst, wrote. "Online chatter is embracing the hype."

"Joker" won the Venice Film Festival's Golden Lion award and has received largely positive reviews.

Paul Dergarabedian, the Comscore senior media analyst, has a more conservative estimate of $50 million-plus, but said the movie will be "more of a marathon runner than a sprinter."

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Buzz is growing for "Joker" a month before its theatrical release.

The upcoming origin story about Batman's greatest nemesis, directed by "The Hangover" director Todd Phillips and starring Joaquin Phoenix, could break multiple records when it comes to theaters on October 4. At this time, Boxoffice Pro is projecting the movie to earn $103 million in its domestic opening weekend, up 27% from its initial estimate.

"Models for 'Joker' continue to improve by leaps and bounds with each passing week," Shawn Robbins, the Boxoffice Pro chief analyst, wrote. "Of notable impact in recent days has been the film's hugely positive reception at Venice Film Festival and the ensuing wave of gushing critics' reviews. Online chatter is embracing the hype."

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"Joker" would pass "Venom" as the biggest October opening of all time if the projection stands, and the first movie to break $100 million in its debut in October.

The movie recently won the Venice Film Festival's Golden Lion award, which is the festival's top prize, and early reviews have been largely positive. It has an 86% critic score on Rotten Tomatoes.

"Having brazenly plundered the films of Scorsese, Phillips fashions stolen ingredients into something new, so that what began as a gleeful cosplay session turns progressively more dangerous — and somehow more relevant, too," The Guardian wrote.

Boxoffice Pro is still cautious about "Joker's" staying power, given "the R-rated film is likely to be divisive among general audiences."

Paul Dergarabedian, the Comscore senior media analyst, has a different outlook this early out. He's projecting a more conservative $50 million-plus domestic opening because it's "not your typical comic-book movie," he told Business Insider.

But he believes that the movie will be "more of a marathon runner than a sprinter," and have legs long after its opening weekend, both domestically and internationally, especially if buzz continues to grow during awards season.

"I'm no less excited or bullish because what really matters is the end of its [theatrical] run," he said. "The opening weekend isn't the end-all, be-all. Sometimes it's hard to gain traction after the opening weekend, but I don't see that being a problem for 'Joker.' All the fans will come out the first weekend, but it will be the ultimate water-cooler movie."