"I don't think it's realistic to try to topple 'Titanic' off its perch. Some pretty good movies have come out in the last few years. 'Titanic' just struck some kind of chord."

That's what [movie id="301495"]"Avatar"[/movie] director [article id="1627584"]James Cameron told MTV News[/article] in early December when asked to compare his upcoming sci-fi epic with his '90s tale of doomed seaborne love, which just so happens to be the highest-grossing movie of all time. One month -- and [article id="1628971"]1 billion box-office bucks[/article] later -- Cameron might have a bit of a different perspective.

After its third weekend of release, "Avatar" has roped in $1.02 billion in worldwide sales, blasting past "The Dark Knight" to land at #4 on the all-time list. Still ahead of Cameron's alien adventure are "Pirates of the Caribbean: Dead Man's Chest" ($1.07 billion), "The Lord of the Rings: The Return of the King" ($1.12 billion) and, of course, "Titanic" ($1.84 billion). So does "Avatar" have what it takes to topple "Titanic"? With the help of BoxOfficeMojo.com, let's take a look at the numbers.

"Titanic" didn't open to a monster haul in mid-December of 1997. It garnered a respectable $28.6 million domestically -- good for the #1 weekend spot, but nothing extraordinary. Where "Titanic" got plain ridiculous was in its staying power: 15 straight weeks on top of the charts, earning over $20 million a week for 10 weeks. In its ninth week of release, it actually jumped 43 percent in total sales. Positive word of mouth and repeat viewership drove the success of "Titanic," as did the typically soft release calendar at the start of any year.

"Avatar," meanwhile, opened big domestically -- $77 million -- though not as big as some had speculated. The next weekend it dropped just 1.8 percent and in its third weekend, just 9.7 percent. Blockbusters can typically fall as much as 60 percent in their second weekend. But as with "Titanic," great buzz and multiple trips to the theater are driving the box-office success of "Avatar."

With just 17 days behind it, "Avatar" seems like a lock to unseat "Dead Man's Chest" and "The Return of the King." But does it have what it takes to reach the top worldwide B.O. spot? Presented in 3-D, the average "Avatar" ticket price is high even by current standards. Additionally, the early 2010 movie calendar is, as usual, slotted with holdovers and other films unlikely to make big splashes. Next weekend's new releases are the Ethan Hawke supernatural thriller "Daybreakers," and the Amy Adams romantic comedy "Leap Year." While Denzel Washington ("The Book of Eli") and Harrison Ford ("Extraordinary Measures") both have films coming out in January, neither projects have garnered much critical or fan buzz. Only Dwayne Johnson, who's had two #1 weekends in a row ("Get Smart" and "Race to Witch Mountain"), seems in a position to challenge "Avatar" for the top weekend spot with the arrival of "The Tooth Fairy" in late January.

For now, we can say that toppling "Titanic" is a serious, though not insurmountable, challenge for "Avatar." What we know for certain is Cameron has become the only director to have two $1-billion grossing films, and two of his films will likely soon hold the top two worldwide box-office spots. And it looks like the director will at least reach his modestly stated goal: "We're hoping 'Avatar' is successful at some level."

Check out everything we've got on "Avatar."

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