By Dean Goodman

LOS ANGELES — "The Forbidden Kingdom," a first collaboration between action heroes Jackie Chan and Jet Li, kicked its rivals at the weekend box office in North America, also becoming the first martial arts movie to open at No. 1 in almost four years.

According to studio estimates issued Sunday, "The Forbidden Kingdom" sold $20.9 million worth of tickets during its first three days, handily exceeding industry forecasts.

Chan and Li play mentors to a modern-day kung fu devotee (played by Michael Angarano) who has been hurled back in time to rural China. It was directed by Rob Minkoff, best known for making the "Stuart Little" family movies. Most critics seemed to like it.

Other debuts included the raunchy romantic comedy "Forgetting Sarah Marshall" at No. 2 with $17.3 million, the Al Pacino thriller "88 Minutes" at No. 4 with $6.8 million, and the Ben Stein documentary "Expelled: No Intelligence Allowed" at No. 9 with about $3.2 million.

Last weekend’s top film, the teen horror "Prom Night," slipped to No. 3 with $9.1 million, taking its 10-day haul to $32.6 million. It was released by Screen Gems, a low-budget division of Sony Corp.

"The Forbidden Kingdom" was released domestically by Lionsgate, a unit of Lions Gate Entertainment Corp, with some financial involvement from the closely held Weinstein Co. Lionsgate had hoped for an opening in the mid- to high-teen millions, said Steve Rothenberg, the studio’s president of domestic theatrical distribution.

Li, who turns 45 on Saturday, starred in the last "chopsocky" chart-topper, "Hero," which opened to $18 million in August 2004. His most recent effort "War," a thriller co-starring Jason Statham, opened at No. 2 last August, with $9.8 million.

Chan, 54, topped the chart last August with the buddy comedy "Rush Hour 3," which opened to $49.1 million, but ended up underperforming its predecessors.

"Forgetting Sarah Marshall" stars Jason Segel, who also wrote the script, as a guy who is dumped by his girlfriend (Kristen Bell). In a rarity for Hollywood films, the critically acclaimed release depicts full-frontal male nudity.

The film’s distributor, Universal Pictures, said the $30 million film opened at the higher end of expectations, and women made up just over half of the audience. It was produced by Judd Apatow, the director of such films as "The 40-Year-Old Virgin" and "Knocked Up." Universal is a unit of General Electric Co’s NBC Universal.

"88 Minutes," filmed two years ago and already released on DVD in some countries, was almost unanimously ripped by critics. Daily Variety said it was "easily" the worst of Pacino’s storied career. It was released by Sony’s TriStar Pictures, which paid $5 million for North American rights and expected to make money on the deal.