Though they came out on top last week, the cast of bruised and battered criminals and ne'er-do-wells that populate "Sin City" were no match for one tanned and toned explorer on a treasure hunt.

"Sahara," the adventure film that stars Matthew McConaughey as a traveler searching for a long lost Civil War battleship, debuted at #1 with $18.5 million, according to early estimates. In the film — adapted from the novel by Clive Cussler — Dirk Pitt (McConaughey) and his partner (Steve Zahn) set out to help Doctor Eva Rojas (Penélope Cruz), who is also eager to find the coin-filled ship, anticipating that it may be linked to a series of unsolved deaths.

Stories of mysterious murders could also be found in the #2 movie at the box office, "Sin City." The film, based on the graphic novels of Frank Miller and starring Bruce Willis, Jessica Alba, Clive Owen and Rosario Dawson, dropped a spot from the #1 position where it debuted last week, bringing in more than $14.1 million.

This week's only other new release, "Fever Pitch," bowed at #3. The romantic comedy, based on the Nick Hornby novel of the same name, stars Jimmy Fallon as a schoolteacher obsessed with the Boston Red Sox, and Drew Barrymore as the businesswoman who falls in love with him (see " 'Fever Pitch' A Home Run, 'Sahara' Just Indy Lite, By Kurt Loder"). In its opening weekend, "Fever Pitch" took in $13 million.

"Guess Who" dropped a spot from #3 to #4 this week, with $7.1 million. The film, an updated version of the 1967 movie "Guess Who's Coming to Dinner," stars Bernie Mac as a protective father whose defenses go up even higher when he finds out his daughter's boyfriend (Ashton Kutcher) is white.

"Beauty Shop" was pushed down to the middle of the box-office top 10 this week, falling three notches from #2 to #5 in its second week in theaters. The film, which stars Queen Latifah as the owner of a beauty shop with a sassy staff and quirky clientele, took in $7.1 million.

For all his perseverance, Rodney — the robot who sets out to make the world a better place in the animated feature "Robots" — couldn't help his film hang on to a spot in the top five at the box office; the comedy dropped from #4 to #6, earning more than $4.6 million.

Rounding out the box-office top 10 this week are "Miss Congeniality 2: Armed and Fabulous," which falls from #5 to #7 with more than $4.1 million; "The Pacifier," which drops from #6 to #8 with more than $3 million; "The Ring Two," which slips from #7 to #9 with $2.9 million; and "The Upside of Anger," which slides from #8 to #10 with $2.6 million.

Overall, ticket sales were down from the corresponding weekend last year.

Next week, look for "The Amityville Horror" to debut on the box-office top 10. Also hitting theaters is "State Property II," directed by Damon Dash and starring Cam'ron, Mariah Carey and the late Ol' Dirty Bastard.

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