Actor Robert Downey Jr. is shown in this undated publicity photo released to Reuters April 23, 2008 in a scene from Paramount Pictures film "Iron Man." [File Photo: Zade Rosenthal/Paramount Pictures/Handout/Reuters]

"Iron Man" clobbered two new releases this weekend to retain the top place at box office in North America, taking in about 50.5 million dollars on its track to become one of the biggest movie hits ever, preliminary figures released Sunday showed.

The Marvel Studios movie, released by Paramount, has already sold an estimated 177 million dollars worth of tickets in two weeks in U.S. and Canadian theaters, and is closing in on the 200-million-dollar mark, according to Los Angeles-based box office tracker Media By Numbers.

Warner Bros.' anime-inspired movie "Speed Racer" finished in second with comparatively weak 20.2 million dollars in its opening weekend, followed by 20th Century Fox's romantic comedy "What Happens in Vegas" with 20 million dollars.

However, the ticket sales figures of the two new releases could change when final weekend tallies are released Monday.

Rounding out the top 5 films this weekend were romantic comedy "Made of Honor" and female comedy "Baby Mama," with 7.6 million and 5.8 million dollars respectively.