LOS ANGELES — Gatsby looks almost as great as a superhero at the weekend box office.
Leonardo DiCaprio’s ‘‘The Great Gatsby’’ partied like it was the Roaring Twenties with a $51.1 million debut that made it a surprisingly strong runner-up to comic-book blockbuster ‘‘Iron Man 3.’’
Studio estimates Sunday put ‘‘Gatsby’’ at No. 2 behind Robert Downey Jr.’s superhero sequel, which pulled in $72.5 million domestically to raise its total to $284.9 million after just 10 days in US theaters.
With an additional $89.3 million in its third weekend overseas, ‘‘Iron Man 3’’ lifted its international total to $664.1 million and its worldwide haul to $949 million.
‘‘The Great Gatsby’’ far exceeded expectations by distributor Warner Bros. of a $35 million to $40 million opening weekend.
Starring DiCaprio in the title role as 1920s mystery millionaire Jay Gatsby, the latest F. Scott Fitzgerald update co-stars Carey Mulligan as his lost love and Tobey Maguire as the friend chronicling their doomed romance.
Director Baz Luhrmann’s 3-D adaptation of the Fitzgerald classic was a rare box-office smash for films aimed at older adults during the youth-minded summer season. According to Warner Bros., viewers over 25 made up 69 percent of the film’s audience.
‘‘It answers the question that you and I hear all the time from people over 50, ‘There’s nothing for me to see,’’’ said Dan Fellman, the studio’s head of distribution. ‘‘While every studio has the $200 million tentpoles in the marketplace, you still have those who feel that it’s not directed at them, which is true. So that’s why I think counterprogramming like this is very important.’’
The weekend’s other new wide release, Lionsgate’s romantic comedy ‘‘Peeples,’’ flopped at No. 4 with just $4.9 million. Produced by Tyler Perry, the movie stars Craig Robinson and Kerry Washington in a meet-the-parents-style farce.
Getting a head start on its domestic launch Friday, ‘‘Star Trek: Into Darkness’’ opened with $31.7 million in seven international markets. Its overseas debut included $13.3 million in Great Britain, $7.6 million in Germany, and $5.5 million in Australia.