Neither a hyper-intelligent robot nor Vince Vaughn could save the box office this weekend, which is down 38.5 percent from the same weekend last year, according to Sunday estimates from box office firm Rentrak.

While Neill Blomkamp's R-rated "Chappie" might have taken the No. 1 spot in its 3,201-screen debut, its modest $13.3 million gross is hardly anything to celebrate. It's a career low for Blomkamp, whose previous films "Elysium" and "District 9" debuted at $29.8 and $37.4 million, respectively.

The R-rated Vince Vaughn comedy "Unfinished Business" fared even worse, opening at No. 10 to a dismal $4.8 million. The $35 million film about a chaotic European business trip also stars Dave Franco and Tom Wilkinson.

In its second weekend, Will Smith's "Focus" fell to second place with $10 million, bringing its domestic total to $34.6 million.

Estimated ticket sales for Friday through Sunday:

1. "Chappie," $13.3 million.

2. "Focus," $10 million.

3. "The Second Best Exotic Marigold Hotel," $8.6 million.

4. "Kingsman: The Secret Service," $8.3 million.

5. "The SpongeBob Movie: Sponge Out of Water," $7 million.

6. "Fifty Shades of Grey," $5.6 million.

7. "McFarland, USA," $5.3 million.

8. "The Lazarus Effect," $5.1 million.

9. "The DUFF," $4.9 million.

10. "Unfinished Business," $4.8 million.

Associated Press