By Lisa Richwine and Patricia Reaney
NEW YORK (Reuters) - Superhero sequel "Iron Man 3" rocketed to the top of U.S. and Canadian box office charts, kicking off Hollywood's summer movie season with $175.3 million in weekend ticket sales for the second-biggest film opening of all time.
Combined with international sales, the movie from Walt Disney Co's Marvel studio brought its global haul to an estimated $680.1 million, Disney said on Sunday.
The film stars Robert Downey Jr. as billionaire businessman Tony Stark, whose superhero alter-ego spars with an evil extremist.
"Iron Man 3" fed off the success of the first two installments plus last year's "The Avengers," a superhero mashup that united Iron Man, The Hulk and other Marvel characters. "Avengers" opened on the same weekend last year with $207.4 million over its first three days, a record for the United States and Canada.
"Iron Man 3" finished second on the all-time list behind "Avengers" and ahead of the July 2011 release of "Harry Potter and the Deathly Hallows - Part 2," which opened with $169.2 million, according to the box office division of Hollywood.com.
"It is an extraordinary start," said Dave Hollis, Disney's executive vice president of distribution. "The start on the U.S. side is something that we are exceptionally proud of."
The $200-million production is another hit for Disney, which is focusing its movie studio on franchise films like "Iron Man" that can spawn movie sequels, toy sales and theme-park rides.
The two previous "Iron Man" movies earned a combined $1.2 billion around the world, according to the Box Office Mojo website.
"Iron Man 3" debuted in international markets starting April 24 to record openings in many countries including China and Russia, generating buzz ahead of its release the United States and Canada.
The big domestic numbers for "Iron Man 3" boosted the overall box office, which is dragging behind 2012 after a sluggish winter and spring.
Studios are counting on summer action films, superhero stories and sequels to lift ticket sales in the coming months. Future releases include sci-fi sequel "Star Trek Into Darkness," Superman reboot "Man of Steel" and robot-versus-aliens action flick "Pacific Rim."
The "Iron Man" mania trounced all other movies over the weekend.
Last week's winner, dark action comedy "Pain & Gain," dropped to second place with $7.6 million. Baseball drama "42" took the No. 3 slot with $6.2 million.
Rounding out the top five, Tom Cruise's post-apocalyptic thriller "Oblivion" grossed $5.79 million, and the animated film "The Croods" rang up $4.2 million.
"Pain & Gain" was released by Paramount Pictures, a unit of Viacom Inc. Comcast Corp's Universal Pictures distributed "Oblivion." Warner Bros., a unit of Time Warner Inc, released "42."
(Reporting by Lisa Richwine and Patricia Reaney; Editing by Cynthia Osterman)