"Avatar" climbed to $601.1 million domestically on Tuesday, putting it a fraction ahead of the $600.8 million haul for "Titanic."
With more than $2 billion worldwide, Cameron's sci-fi sensation shattered the global box-office record of $1.84 billion held by "Titanic" last week.
"When some said to us, `How is it going to feel to knock off `Titanic'? I think our response was, `It's about time those guys got knocked off their perch,"' said Cameron's producing partner Jon Landau on Tuesday, after "Avatar" tied for the lead at the Academy Awards with nine nominations, including best picture.
"Lightning is not supposed to strike twice. And it has. And it's a pinch-me moment when you sit there and you hear that we're going to break another record. It's beyond anything that we could have imagined," he said.
Landau said he, Cameron and their collaborators have discussed sequel prospects but that nothing definite has been decided. Just before the release of "Avatar" in December, writer-director Cameron said he had the "broad strokes for two more films."
"This is set up to be a potential franchise," Cameron had said in December. "It's not like I've got scripts two and three teed up, ready to go, and I want to start at the end of January. But it's definitely part of the game plan."
"Avatar" still has plenty of box-office life left. It passed $600 million domestically on its 47th day of release. Back in 1998, "Titanic" was at barely half that amount -- $311 million -- after its 47th day in theaters.
Factoring in today's higher admission prices, "Titanic" still has sold more tickets than "Avatar."
Adjusted for inflation, classics such as "Gone With the Wind," "Star Wars" and "The Sound of Music" still top the charts for most tickets sold.
Landau, a producer on both "Titanic" and "Avatar," said he does not buy into inflation-adjusted box-office rankings, adding that "every movie has to stand in its own time."
"`Gone With the Wind' didn't have to compete with television. `Star Wars' didn't have to compete with DVDs. `Titanic' didn't have to compete with Blu-rays and satellite. So I think every film has to compete on its own merits," Landau said.
"The inflation argument, I find it funny when people raise it, 'cause I never heard them raising it when they talk about budget and cost to the movie. But they love to do it when it comes to box office," he said.