Los Angeles ? The Will Ferrell comedy “Talladega Nights: The Ballad of Ricky Bobby” raced ahead of the competition to remain the box office champ for a second weekend with $23 million in ticket sales, according to studio estimates released Sunday.

Last week’s news of another terror plot against airliners apparently did not dampen audience appetite for Oliver Stone’s “World Trade Center.” The Paramount Pictures release beat expectations by earning $19 million over the weekend to place it third at the weekend box office.

The shocker of the weekend was the high-school dance film “Step Up” from The Walt Disney Co., which placed second with a box office take of $21 million.

“It stepped up out of nowhere and surprised everyone,” said Paul Dergarabedian, president of box office tracker Exhibitor Relations. “It was totally unexpected.”

Disney flooded the Internet and music television networks with dance videos from the film, a strategy that broadened the audience from the target female teen demographic. While 70 percent of the audience was female, about one-quarter was in the 18-24 age range, according to exit polling.

The performance of the top 12 films was up 6.35 percent from the same weekend last year, making it the fourth weekend in a row that the box office has outpaced last year’s levels.

Diversity played a big role in generating attendance, analysts said.

“There is so much variety. You pick a genre and you can find a movie,” Dergarabedian said.

Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Exhibitor Relations Co. Inc. Final figures will be released Monday.

1. “Talladega Nights: The Ballad of Ricky Bobby,” $23 million.

2. “Step Up,” $21 million.

3. “World Trade Center,” $19 million.

4. “Barnyard,” 10.1 million.

5. “Pulse,” $8.5 million.

6. “Pirates of the Caribbean: Dead Man’s Chest,” 7.2 million.

7. “Zoom,” 4.6 million.

8. “The Descent,” $4.6 million.

9. “Miami Vice,” $4.5 million.

10. “Monster House,” $3.3 million.