Tina Fey and Amy Poehler's comedy "Baby Mama" about a woman and her surrogate mother easily delivered more than $18 million for Universal Pictures, also marking the first top opener for the studio this year.

The humorous approach to an increasingly popular drama of today's career-focused society starring the "Saturday Night Live" duo earned $4 million above the estimated sum, crawling past Warner Bros.' "Harold & Kumar Escape from Guantanamo Bay," another goofy stoner flick that opened at No. 2 with $14.6 million.

More than two-thirds of Mama's audience was female, while Harold lured the same percentage of male moviegoers.

"Sorry, guys, but this was a ladies' weekend," said Nikki Rocco, distribution chief for Universal Pictures. Tina Fey "is a real talent. She's showing she can do TV and the movies really well."

Lionsgate's Jet Li-Jackie Chan adventure fantasy "Forbidden Kingdom," which topped last weekend's box office, narrowly edged out Universal's second comedy "Forgetting Sarah Marshall" to take the No. 3 spot, declining 48% in its second sesh to an estimated $11.2 million 3,151 runs. "Sarah Marshall" held its own at No.4 with $11 million. It dropped 38 percent from last weekend, an indication of positive word of mouth. The comedy opened at No. 1 in the U.K. this weekend with $4.1 million, Universal said.

Although unusual for a studio to open two comedies back-to-back, Universal said the stellar hold of the R-rated "Sarah Marshall" shows that it wasn't hurt by the entry of "Baby Mama," and vice versa. "Sarah Marshall" appealed to men more than "Baby Mama."

In the meantime, the "Harold & Kumar" which sequel cost just $12 million to make is already close to beating the entire theatrical take of $18.2 million for the first movie.

"Given all the female comedies out there, we couldn't be happier," Warner Bros.' Dan Fellman said. "We know most of the people who came were 18 to 35, but we didn't check how many were on parole."

Rounding up the top five, "Nim's Island,'' based on the book by Wendy Orr, stayed in fifth with sales of $4.5 million. The movie from News Corp. follows the adventures of a young girl who lives on a remote island with her family. She joins forces with her favorite author to find her missing father. Jodie Foster and Gerard Butler co-star. It has made $39 million in three weeks of release.

Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Media By Numbers LLC. Final figures will be released Monday.

1. "Baby Mama," $18.3 million.
2. "Harold & Kumar Escape from Guantanamo Bay," $14.6 million.
3. "The Forbidden Kingdom," $11.2 million.
4. "Forgetting Sarah Marshall," $11 million.
5. "Nim's Island," $4.5 million.
6. "Prom Night," $4.4 million.
7. "21," $4 million.
8. "88 Minutes," $3.6 million.
9. "Dr. Seuss' Horton Hears a Who!", $2.4 million.
10. "Deception," $2.2 million.