"Iron Man" was the second biggest movie of 2008 and, if early tracking is to be believed, "Iron Man 2" has a chance to unseat "The Dark Knight" — and its $158.4 million — on May 7 as the movie with the biggest domestic opening weekend of all time. Is it any wonder, then, that talk has already turned to "Iron Man 3"?

Marvel Studios has a busy couple years ahead of it, with "Captain America: The First Avenger" and "Thor" coming in 2011, and "The Avengers" due in 2012, but Robert Downey Jr. assured MTV News that "Iron Man 3" will happen ... eventually.

"I think it's going to go down," the man behind Tony Stark said on Monday, hours before the "Iron Man 2" premiere.

Though "Avengers" is "supposedly first on [Marvel's] docket," Downey went on to note that he's already got some thoughts about where he wants the "Iron Man" franchise to head in its third installment.

"I have some pretty strong ideas, but they never seem to be too discordant with what the creative execs at Marvel are thinking anyway," he said.

While Downey didn't go into detail about those ideas, he may have been referring to the "Demon in a Bottle" storyline, which originated in 1979. Longtime "Iron Man" comics writer Bob Layton told MTV News that "Iron Man 3" may incorporate a plotline in which Stark battles a debilitating addiction to alcohol. Mining the rich history of existing "Iron Man" plotlines — the character was created in the early '60s — is simply the best way to create compelling stories for the big screen, said Downey, who supported the same approach for last year's "Sherlock Holmes."

"It's all there," he said. "There's a little bit of a bunch of different storylines from different decades. I always feel, just like with 'Sherlock,' you're not going to do any better than you will looking back at [Arthur Conan] Doyle's stories."

Though the actor confessed that he's no authority on the Marvel universe, he knows enough — and there are true authorities on hand to fill in the blanks. "I act as though I'm the technical expert," he laughed. "What I am is the expert on me and Tony and Iron Man. Once it starts intersecting with the other stuff, I lose track. Thankfully, there are experts."

What would you like to see in a third "Iron Man" movie? Share your ideas in the comments.

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