Endgame is a climax of sorts to the 21 previous titles in the Marvel Cinematic Universe (MCU), a blockbuster series of films that commenced with the breakout hit Iron Man in 2008 and established Kevin Feige's Marvel Studios as the best in the show.

The tentpole is a direct sequel to Avengers: Infinity War, which opened to $257.6 million in late April 2018, marking the biggest North American launch of all time ahead of Disney and Lucasfilm's Star Wars: The Force Awakens ($248 million).

Globally, Infinity War launched to a record-shattering $640.5 million. That was without China, where it opened two weeks later to a massive $191 million. Endgame opens day and date in almost every major market across the globe, including China.

In Latin America, Endgame has broken the MCU's tickets presale record with 5 million tickets sold in one week, according to Disney Latin America. Last week, Fandango's LatAm subsidiary reported that Endgame was the company's most successful presale in the region, a mere hours after tickets became available online.

The big question mark — Endgame runs three hours and one minute, the longest of any MCU title and meaning one fewer showtime a day, on average (Infinity War was two hours and 29 minutes).

Disney and Marvel can make up the difference by booking even more screens for the superhero extravaganza, directed by the Russo brothers.

So far, early tracking shows Avengers: Endgame debuting domestically to $200 million to $260 million. However, when the movie sold more advance tickets in its first 24 hours than any picture in history, the speculation spiraled. Box office sources tell THR they believe a realistic range is $250 million to $280 million.

Adds Paul Dergarabedian of ComScore, "like some sort of box office unicorn, the opening weekend speculation surrounding Endgame has taken on mythical proportions. No matter the actual number, the fact that people are putting this crazy $300 million number into the ether shows how much enthusiasm and excitement there is for what is arguably the most anticipated Marvel movie ever."

When Infinity War first came up on track, it was tipped for a debut of $185 million to $225 million.

One potential competitor for Endgame will be the third episode of HBO'S Game of Thrones, which airs Sunday nights.

"The weekend of April 26 for many people will be like having the Super Bowl, the Oscars and their Birthday all on the same weekend," says Dergarabedian, "Fortunately for Avengers and GOT fans, there is more than enough time to enjoy both."

Atom Tickets reported Tuesday morning that Endgame has sold twice as many advance tickets in its first week than its four previous biggest sellers combined; Aquaman, Star Wars: The Last Jedi, Avengers: Infinity War and Captain Marvel.

April 9, 9:00 a.m. Updated with Atom Tickets sales.

A previous version of this story incorrectly characterized China’s opening. THR regrets the error.