Looks like James Cameron might not have to take out another ad congratulating "Avengers: Endgame" for surpassing one of his films on the all-time box-office chart.

While "Endgame" smashed all kinds of opening records (including taking down "Titanic,") it hasn't yet passed "Avatar"s all-time haul of $2.78 billion. (After four weeks, it stands at $2.62 billion in worldwide ticket sales.)

"It’s slowed down more than we all expected," Shawn Robbins, chief analyst at BoxOffice Media told THR of the hit Marvel movie.

Robbins first expected "Endgame" to eclipse "Avatar"’s record in mid-June. Now he thinks it may not happen until Labor Day, if at all.

"Avatar" spent 7 weeks as the number one film, compared to "Endgame's 3-week reign. It was also a steady earner, spending over 60 weeks in theaters and receiving a late summer re-release more than half-of-a-year after its December debut.

"Endgame" doesn't appear to have that kind of staying power so far.

"If it 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,' said Robbins, adding, "But it would be surprising if Disney didn’t get it there somehow."

Hmm, perhaps a rerelease with extra scenes would put it over the top?

Something that wasn't true when "Avatar" was just up against "Iron Man:" With Disney's purchase of 20th Century Fox's assets, both franchises are now Disney properties. Per CNET, one of the reasons the long-awaited "Avatar" sequels are taking so long is they're now being spaced out between Marvel and "Star Wars" movies.

Whichever film ends up on top, Zoe Saldana, who mo-capped Neytiri in "Avatar" and played Gamora in "Endgame," remains a box office queen.

[Via THR]