Avengers: Endgame Now Not Expected to Catch Avatar Until Labor Day

Avengers: Endgame beating out James Cameron's Avatar as the highest-grossing movie of all time might be unattainable — or Unobtanium — as industry experts now predict the slowing Marvel Studios blockbuster won't reach the #1 worldwide spot until Labor Day, if it makes the mark at all.

"It's slowed down more than we all expected," BoxOffice Media chief analyst Shawn Robbins told THR.

After its record $357 million domestic opening weekend and $1.2 billion global debut, Robbins initially expected the Anthony and Joe Russo-directed blockbuster to unseat Avatar's $2.78 billion record by mid-June. Now Robbins says if Endgame topples Avatar, it's more likely to happen early September.

"No movie had opened on that level, globally," Robbins said of Endgame, which has amassed a $2.62 billion global haul as it stares down the summer movie season.

Paul Dergarabedian, senior media analyst at ComScore, said both films had polar opposite releases: Avatar opened December 2009 and spent 60 weeks in theaters with lighter competition.

"Avatar was all about the marathon and now it's about the sprint," Dergarabedian said. But the front-loaded Endgame did a "lion's share of its business in the first few weeks," Robbins added.

Another consideration is the growth of the international box office in the decade separating Avatar and Endgame. The $204m won by Cameron's blockbuster in China was just 7 percent of that film's total global box office, where Endgame's $608m haul from China totals 23 percent of its global box office to date.

Legendary's Pokémon Detective Pikachu and Lionsgate's John Wick: Chapter 3 helped hobble Endgame at the international and domestic box offices, and Earth's mightiest heroes will face steeper competition with the arrival of Disney's own Aladdin (now playing), Warner Bros.' Godzilla: King of the Monsters (May 31), Fox's (now Disney's) Dark Phoenix (June 7), and Disney-Pixar's Toy Story 4 (June 21).

By July, Sony-Marvel's Spider-Man: Far From Home (July 2) and Disney's The Lion King (July 19) will dominate theaters.

"If [Endgame] performs like it has been up to this point, there is about a $10 million to $20 million margin that falls half north and half south of Avatar," Robbins said. "But it would be surprising if Disney didn't get it there somehow."