LOS ANGELES (Reuters) - "How to Train Your Dragon" proved a difficult film to slay at the North American box office as it took the top spot in its fifth weekend in theaters, according to studio estimates issued on Sunday.
The animated "Dragon" earned $15 million over the weekend since Friday, dropping just 23 percent since last weekend.
Romantic comedy "The Back-up Plan" followed at No. 2 with $12.3 million, while action comedy "The Losers" opened at No. 4, slightly short of expectations with $9.6 million.
"We couldn't be more thrilled to be No. 1 in the fifth week," said Anne Globe, head of worldwide marketing for DreamWorks Animation SKG Inc, the studio that produced "Dragon."
"The Back-up Plan," which is Jennifer Lopez's first movie appearance since 2006, opened within industry expectations. The singer and actress stars opposite Alex O'Loughlin.
The release from CBS Corp's film division was made for $35 million. It ruled the Friday night box office, but later lost the lead to "Dragon" as families streamed into matinee showings of the animated film.
"Date Night," a romantic comedy from News Corp-owned Twentieth Century Fox, remained a solid performer in its third weekend. It made $10.6 million, which was only a 37 percent drop from last week and claimed the No. 3 spot.
CBS Films expects "The Back-up Plan" to follow the pattern set by romantic comedies such as "Date Night."
"Romantic comedies have been over-performing this year and in the second and third and fourth week, Jennifer Lopez films tend to over-perform and have great legs, as does Jennifer herself I might add," said Steven Friedlander, executive vice president, distribution, for CBS Films.
With no big budget movie openings, the overall box office for the weekend was under $100 million, which was the lowest total of the year, said Paul Dergarabedian, president of tracking firm Hollywood.com Box Office.
"The Losers," an ensemble action comedy with Chris Evans, Zoe Saldana, Jeffrey Dean Morgan and Idris Elba, was made on a modest budget of $31 million, said the studio behind the film, Time Warner Inc's Warner Bros.
The movie about an armed U.S. special forces team is based on a comic book series, and comes out of the DC Entertainment division of Warner Bros.
"Kick-Ass," another action comedy which last weekend also opened below expectations, failed to stage a comeback as it ended the weekend with an estimated $9.5 million. That was a drop of 52 percent.
"Kick-Ass" is from Lions Gate Entertainment Corp, The movie's mediocre performance comes at a difficult time for Lions Gate, which faces a hostile $7 per share takeover bid from billionaire investor Carl Icahn.
"Dragon," which is distributed by Viacom Inc's Paramount Pictures division, narrowly lost the box office race last week to "Kick-Ass."
"Dragon" has made 67 percent of its total $178 million U.S. and Canada gross from 3-D screenings. The two films that ruled this year's box office more often than "Dragon" are "Avatar" and "Alice in Wonderland," and they were also in 3-D.
DreamWorks expects "Dragon" to continue to stay strong for the next two weeks, in advance of the summer movie season.
Reporting by Alex Dobuzinskis: Editing by Jackie Frank