Los Angeles ? The first-time director and cast of unknowns of the acclaimed sci-fi thriller “District 9” have given Hollywood a late-summer box-office boost.

The Sony release produced by “Lord of the Rings” director Peter Jackson led the weekend with a $37 million debut, according to studio estimates Sunday.

“District 9” is the debut feature from commercial and music-video director Neill Blomkamp, who co-wrote the tale about extraterrestrials forced by humans to live in squalor in a ghetto in South Africa.

The movie built audience interest with a clever marketing campaign playing up the theme of prejudice against aliens, including posters instructing citizens to report non-humans and ads on bus benches stating that the seats are for humans only.

The previous weekend’s No. 1 movie, Paramount’s “G.I. Joe: The Rise of Cobra,” slipped to second place with $22.5 million, raising its 10-day total to $98.8 million.

Another sci-fi tale, the Warner Bros. romance “The Time Traveler’s Wife” starring Eric Bana and Rachel McAdams, opened a solid No. 3 with $19.2 million.

Estimated ticket sales are for Friday through Sunday at U.S. and Canadian theaters, according to Hollywood.com.

1. “District 9,” $37 million.

2. “G.I. Joe: The Rise of Cobra,” $22.5 million.

3. “The Time Traveler’s Wife,” $19.2 million.

4. “Julie & Julia,” $12.4 million.

5. “G-Force,” $6.9 million.

6. “The Goods: Live Hard, Sell Hard,” $5.4 million.

7. “Harry Potter and the Half-Blood Prince,” $5.2 million.

8. “The Ugly Truth,” $4.5 million.

9. “Ponyo,” $3.5 million.

10. “500 Days of Summer,” $3 million.