Kutcher, Portman comedy tops box office

Audiences weren't afraid of committing to "No Strings Attached," making it the No. 1 movie at the box office in its opening weekend.

The romantic comedy from Paramount Pictures earned an estimated $20.3 million, according to studio reports released Sunday.

Ashton Kutcher and Natalie Portman star as friends who try to maintain a purely sexual relationship, even as they're falling in love.

Last week's No. 1 movie, Columbia Pictures' action comedy "The Green Hornet," dropped to second with $18.1 million. It has now made $63.4 million total. Seth Rogen stars as the playboy-turned-superhero, based on the 1930s radio show, with Taiwanese pop star Jay Chou as his sidekick, Kato.Portman just won a Golden Globe award for her portrayal of a ballerina gone mad in "Black Swan," the weekend's sixth-highest grossing film, and for which she's likely to receive an Academy Award nomination Tuesday. She recently announced she's expecting a baby with her fiance, Benjamin Millepied, who choreographed "Black Swan" and has a cameo in it.