The Robert Downey Jr. sequel scored an estimated $15.6 million in its domestic debut, upping its worldwide total to a fast and furious $361 million.
Internationally, the film is already its franchise's top-grossing entry.
The movie's reported midnight Friday take, which, per the new Hollywood standard, includes business from Thursday preview screenings, is likewise an Iron Man best.
The 2008 original grossed a relatively mortal $1.5 million from midnight screenings; 2010's Iron Man 2 grew to $7.5 million, but was still a long way away from the all-time night-owl champs.
Iron Man 3 was no Harry Potter or Dark Knight itself, but it did put up an Avengers-comparable number—and it's never a bad thing to be on the heels of Hollywood's opening-weekend record-holder.
On the whole, Iron Man 3 is expected to be headed for a three-day weekend domestic gross north of $150 million.
Here's a look at the top 10 midnight box-office openers, as compiled by Hollywood.com:
Harry Potter and the Deathly Hallows: Part 2, $43.5 million
The Dark Knight Rises, $30.6 million
The Twilight Saga: Breaking Dawn Part 2, $30.4 million (includes Thursday previews)
The Twilight Saga: Breaking Dawn Part 1, $30.3 million
The Twilight Saga: Eclipse, $30 million
The Twilight Saga: New Moon, $26.3 million
Harry Potter and the Deathly Hallows: Part 1, $24 million
Harry Potter and the Half-Blood Prince, $22.2 million
The Hunger Games, $19.7 million
The Avengers, $18.7 million
Per Hollywood.com's count, Iron Man 3 ranks 13th.
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Again I'll ask this question, for those who have seen it, how was the movie?