Seth Rogen in 'Funny People'

Seth Rogen in 'Funny People'

"Funny People" generated the box office equivalent of a light chuckle, opening to a studio-estimated $23.4 million on its opening weekend.

That's below what tracking had indicated and what some of the biggest summer comedies starring Adam Sandler ("You Don't Mess with the Zohan") -- and Seth Rogen ("Superbad") -- have done. Given the concerns of many in Hollywood that audiences would react very poorly to the Judd Apatow-directed comedy's dark tone and long running time, however, it's no disaster for a movie that cost Universal Studios and Relativity Media $75 million to produce.

The opening weekend performance didn't resolve questions about whether "Funny People" will hold on well at the box office going forward. The Friday-Saturday drop was 15%, a mixed territory that has historically included some movies that played well for a while, like "Superbad," and others like "Wolverine" that fell off fast.

"Aliens in the Attic," the weekend's other new picture, was a clear-cut miss, opening to just $7.8 million. Fox and New Regency spent $45 million on the family comedy.

Disney's guinea pig action flick "G-Force" had a decent second weekend drop of 45%, putting it in second place with $17.1 million. The movie was expensive to produce at $150 million, however, and Disney had been hoping for an even smaller drop to help avoid it turning into a money loser. After solid weekday ticket sales, "G-Force" has now grossed a total of $66.5 million.

"The Ugly Truth" didn't fare as well, declining a more dramatic 53% on its second weekend to $13 million, a signal that it won't have a long and prosperous box office run like other recent romantic comedies, including "The Proposal."

"Harry Potter and the Half-Blood Prince" got a boost from expanding into 162 new Imax theaters this week and declined only 40% on its third weekend to $17.7 million. After initially falling behind predecessor "Harry Potter and the Order of the Phoenix" when accounting for inflation, it's now gaining ground.

Here's the top 10:

1. "Funny People'"- $23,440,000

2. "Harry Potter and the Half-Blood Prince" - $17,700,000

3. "G-Force" - $17,058,000

4. "The Ugly Truth" - $13,000,000

5. "Aliens in the Attic" - $7,800,000

6. "Orphan" - $7,250,000

7. "Ice Age: Dawn of the Dinosaurs" - $5,300,000

8. "The Hangover" - $5,080,000

9. "The Proposal" - $4,848,000

10. "Transformers: Revenge of the Fallen" - $4,600,000