LOS ANGELES ? ?Iron Man 3? is the heavy-lifter at theaters with a colossal overseas debut that overshadows a sleepy pre-summer weekend at the domestic box office. The superhero sequel starring Robert Downey Jr. got a head-start on its domestic launch Friday with a $195.3 million opening in 42 overseas markets. Studio estimates show director Michael Bay's true-crime tale ?Pain & Gain? muscled into first-place domestically with a $20 million debut. The movie starring Mark Wahlberg, Dwayne Johnson and Anthony Mackie knocked off Tom Cruise's sci-fi adventure ?Oblivion? after a week in the No. 1 spot. ?Oblivion? slipped to second-place with $17.4 million, raising its domestic total to $64.7 million.