The summer movie season will kick off early this weekend with “Avengers: Infinity War,” the third installment in Disney and Marvel Studios’ sprawling “Avengers” saga that may push the Marvel cinematic universe to new heights.

The superhero release is expected to easily conquer the weekend box office, giving a much-needed jolt to domestic sales, which so far this year are down nearly 3 percent from the same period last year, according to ComScore data.

Some analysts estimate the movie could have a global box-office pull of as much as $500 million, which would be one of the largest launches in film history.

“Avengers: Infinity War” is about the furthest thing from a box-office gamble that the movie business has to offer. It’s the third “Avengers” movie and the 19th movie from Marvel Studios, which Burbank-based Walt Disney Co. purchased in 2009 as part of its $4-billion acquisition of Marvel Entertainment.

The new movie is expected to gross about $225 million in the U.S. and Canada from Thursday night through Sunday, according to people who have read pre-release audience surveys.

That would make it one of the biggest opening weekends ever. (Disney’s projections are slightly more conservative, at $210 million for the premiere weekend.) Advance ticket sales have been extraordinarily strong. Earlier this month, the largest online ticket seller, Fandango, said the film was outpacing pre-sales for the last seven Marvel movies, combined.

“Advanced ticket sales for ‘Infinity War’ … are beyond anything we have seen before,” said John Fithian, president of the National Assn. of Theatre Owners, at CinemaCon in Las Vegas, the industry’s annual conference.

If “Infinity War” hits the $225-million mark, the superhero mashup would have the second-highest opening ever, not adjusted for inflation, topping the $220-million bow of 2017’s “Star Wars: The Last Jedi.” The all-time top opening remains 2015’s “Star Wars: The Force Awakens,” which launched with $248 million. Some analysts have boldly suggested “Infinity War” could take the all-time crown, though openings of that size are notoriously difficult to predict with precision.

“Infinity War” is likely to easily surpass the previous April opening weekend record of $147.2 million set by Universal’s “Furious 7” back in 2015, according to Paul Dergarabedian, senior media analyst at ComScore.

Disney would not give a prediction for “Infinity War’s” overseas box office sales, but all indications are that it will be popular globally when it opens in key markets including South Korea, Britain and Spain this weekend. If it does as well as 2015’s “Avengers: Age of Ultron” — the second “Avengers” movie — it could gross as much as $250 million internationally in its opening. It launches in China, the world’s second-largest box-office market, on May 11.

The reason for the excitement: fans’ loyalty to the Marvel cluster of movie heroes. This time, it’s not just Avengers regulars like Iron Man, Thor and the Hulk returning to battle villain Thanos. “Infinity War” also brings obscure-turned-bankable characters such as Doctor Strange and the Guardians of the Galaxy into the mix.

One might think the influx of heroes could result in a cinematic superhero turducken of differing styles, tones and back stories. But reviews so far have been strong, marked by an 86 percent “fresh” score on Rotten Tomatoes.

“Infinity War” is the latest blockbuster from Disney’s Marvel Studios, which has enjoyed a remarkable string of hits based on its connected web of comic book characters. “Avengers: Age of Ultron” grossed $1.4 billion at the worldwide box office after opening with $191.3 million in the U.S. and Canada. The first, “The Avengers,” collected almost $1.52 billion total.

Despite predictions of superhero fatigue, the Marvel characters have only become more popular—and diverse—since the last Avengers movie. February’s “Black Panther” shattered myths about the global playability appeal of movies with black casts, grossing $1.3 billion worldwide, greatly exceeding industry expectations. Black Panther’s presence in “Infinity War,” which is emphasized in trailers, has stoked even more anticipation for the blockbuster.

The box-office power of “Infinity War” is also changing Hollywood’s calendar. Many observers consider it the beginning of the summer movie season, even though the summer box office usually starts the first weekend of May.

It’s poised to kick off a strong couple of months for movie theaters, with a release schedule packed with major films such as “Deadpool 2,” “Solo: A Star Wars Story” and “Jurassic World: Fallen Kingdom.” This summer is expected to be significantly better for the domestic box office than last summer, according to analysts. That would be a relief for cinema owners, who suffered the worst sales in more than a decade in summer 2017.

“The movie run that’s beginning this summer is tremendous and it’s diverse and it’s wonderful,” Fithian said at CinemaCon. “[The audience is] going to ‘Infinity War,’ one of the biggest openings of all time, and they’ll see the trailers for the movies coming out in the next three or four months.”

A fourth “Avengers” movie is scheduled to hit theaters next year. The untitled release will follow two other Marvel superhero movies — the upcoming “Ant-Man and the Wasp” and 2019’s “Captain Marvel.”