George Clooney’s latest enthusiastic directorial effort, sports comedy “Leatherheads,” failed to bring hordes of moviegoers to the cinema in its opening weekend, scoring a modest $13.5 million.

Faced with a choice between the newly released 1920s comedy about American football players “Leatherheads” and modern gambling film “21,” which opened last week, North American moviegoers settled on the second alternative.

Columbia Pictures’ “21,” starring Jim Sturgess, Kate Bosworth and Kevin Spacey, was No. 1 at the North American box office, earning $15.1 million in ticket sales. Its opening weekend at the end of March was worth $24 million and was atop the box office charts.

“Leatherheads,” directed and co-written by George Clooney, who also stars alongside Renee Zellweger and Josh Krasinski, failed to draw big crowds, for reasons which seem to elude the film’s distributor as well.

“I’m disappointed for us; I’m disappointed for George,” said Nikki Rocco of Universal Pictures. “I think he’s a great guy and think he’s got tons of directing talent. I wish I could have that crystal ball and tell you what went wrong.”

This is Clooney’s third time as director. His first attempt, 2002’s “Confessions of a Dangerous Mind,” was well received by critics but also fared poorly at the box office. Clooney’s next effort, “Good Night and Good Luck,” received six Academy Award nominations, including for Best Picture, Director, and Actor.

In third place this weekend was another debut, this time the children’s adventure film “Nim’s Island,” starring Academy Award nominee Abigail Breslin and two-time Oscar winner Jodie Foster. The 20th Century Fox film earned $13.3 million, according to box office tracker Media by Numbers.

Animated film “Dr Seuss’ Horton Hears A Who!” slipped two places to four and earned another $9.1 million. It was followed at No. 5 by horror movie “The Ruins,” which opened with $7.8 million.