San Diego, California - Ryan Reynolds and Hugh Jackman kicked off celebrations at the giant Comic-Con pop culture gathering Thursday with a special screening of Deadpool & Wolverine, their smutty superhero mash-up movie expected to break box office records this weekend.

The Hollywood A-listers took the stage before 6,000 screaming fans – many dressed as spandex-clad heroes and villains – who had won a lottery to attend the hot-ticket opening night event in San Diego, California.

The film brings together two wildly popular characters from the Marvel superhero movies. Reynolds's potty-mouthed Deadpool teams up with Jackman's grizzled Wolverine, from the X-Men movies.

It is widely expected to be one of the year's highest-grossing films.

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"A Deadpool and Wolverine movie is quite literally something that I feel like I've waited my whole life for," said Reynolds, before introducing a surprise screening of the entire movie.

"We've been around the world with this movie, but the icing on the cake is right here, right now," added Jackman.

Out in theaters globally this weekend, Deadpool & Wolverine is expected to shatter the box office record for movies with an R rating – meaning children cannot attend without an adult.

Reynolds' anti-hero frequently "breaks the fourth wall" by speaking directly to audiences, cracking sexually explicit jokes, and sarcastically mocking the Marvel franchise and its studio Disney.

The film could gross as much as $200 million in North American theaters on its opening weekend alone, trade magazine Variety suggested.

The current record for R-rated films is held by the original Deadpool, which made $132 million in its first weekend in 2016, after also getting a Comic-Con preview.

"I remember making that movie for you," Reynolds told the die-hard superhero fans who make the pilgrimage each year to San Diego. "And I remember how gratifying it was that everyone else liked it too."

One of the world's largest pop culture events, Comic-Con began five decades ago as a humble comic book-themed gathering in a hotel basement.

Today it draws A-list stars.

Also on Thursday, Chris Hemsworth attended a panel for animated prequel Transformers One, while director Roland Emmerich promoted his racy new Ancient Rome-set drama Those About To Die.

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It is a contrast to last year's edition, where Hollywood strikes prevented actors from attending, and quelled much fan interest.

This time around, Comic-Con is expected to draw 135,000 attendees back to the southern Californian city.

Disney on Saturday will also host a hugely anticipated Marvel presentation that is expected to unveil wider plans to reboot its mega-grossing superhero films, after recent high-profile missteps.

The Marvel movies dominated Hollywood and global box offices for years, with 2019's Avengers: Endgame briefly becoming the highest-grossing film of all time at more than $2.79 billion.

But the past few years have brought more flops than hits, as fans complained about over-complicated plotlines and mourned the departure of favorite characters like Robert Downey Jr.'s Iron Man.

The franchise has been rocked by domestic violence revelations about actor Jonathan Majors, who had been set to become the major new supervillain across multiple films.

Majors, who was convicted for assaulting his then-girlfriend, has been dropped by Marvel, but plans to replace him are yet to be revealed.

Also this week, crowds will get a look at Alien: Romulus, the latest in the long-running sci-fi saga launched by Ridley Scott with 1979's Alien.

Disney's rival studio Warner will offer a glimpse at its Batman spinoff TV series The Penguin, starring Colin Farrell.

Amazon's Prime Video will lift the lid on the second season of its Lord of the Rings television series, which aims to improve on the mixed reviews for its hugely expensive debut season two years ago.

Comic-Con runs until Sunday.