Avatar is showing no signs of slowing down at the box office. The sci-fi story was number one for the fourth weekend in a row, earning an estimated 48.5 million dollars. It's a record total for a movie's fourth weekend in release, surpassing the 28.7 million collected in 1997 by another James Cameron blockbuster, Titanic. 

Avatar currently is the second highest-grossing movie of all time worldwide, having raised 1.34 billion dollars so far, trailing only Titanic. It also ranks sixth all time at the domestic box office, with 429 million. Avatar, which debuted in mid-December, is also the top-grossing movie of any 2009 release. 

Holding steady in the second and third spots over the weekend were Sherlock Holmes and Alvin and the Chipmunks: The Squeakquel. The vampire-themed thriller Daybreakers had the most successful debut, opening at number four with 15 million dollars. The Amy Adams romantic comedy Leap Year premiered in sixth place, with 9.2 million bucks, and the Michael Cera comedy Youth in Revolt bowed at number nine, with seven million.

Here are the top 10 movies from Friday through Sunday, with estimated ticket sales: 

1. Avatar, $48.5 million.
2. Sherlock Holmes, $16.6 million.
3. Alvin and the Chipmunks: The Squeakquel, $16.3 million.
4. Daybreakers, $15 million.
5. It's Complicated, $11 million.
6. Leap Year, $9.2 million.
7. The Blind Side, $7.8 million.
8. Up in the Air, $7.1 million.
9. Youth in Revolt, $7 million.
10. The Princess and the Frog, $4.7 million.