Looks like America was more interested in Robert Downey Jr. than Tom Cruise this weekend as “Sherlock Holmes” took the box office cake, bringing in $40 million. Read the full report after the jump!

Wendy L.

EW:

Hollywood’s autumn blues continued as the box office trailed 2010 for the fourth week in a row. Thanks to the surprisingly soft debuts of Sherlock Holmes: A Game of Shadows and Alvin and the Chipmunks: Chipwrecked, this weekend’s top dozen movies earned about 13 percent less than last year’s. Luckily, next week brings us The Adventures of Tintin, The Girl With the Dragon Tattoo, We Bought a Zoo, and the wide expansion of Mission: Impossible — Ghost Protocol. If those movies can’t lift the business out of the gutter, then Hollywood better start revising its New Year’s resolutions.

Warner Bros.’ Sherlock Holmes: A Game of Shadows, starring Robert Downey Jr. and Jude Law, won the weekend with an estimated $40 million. That’s a steep drop from the 2009 original, which debuted to $62.3 million. It’s worth pointing out that the first movie opened on Christmas Day weekend, which helped to inflate its numbers. A Game of Shadows, on the other hand, opted for the weekend before Christmas — a much tougher frame due to the fact that many moviegoers are currently occupied with holiday preparations.

Still, most box-office prognosticators thought the $125 million sequel would at least generate $50 million this weekend. The PG-13 movie, which received middling reviews, will now have to hope it has sturdy legs throughout the holiday. One good sign is that A Game of Shadows received an “A-” grade from CinemaScore audiences, so word of mouth should be positive. As expected, the film skewed male, with men making up 59 percent of the audience. Also, as has been the case with many big movies this year, A Game of Shadows had trouble attracting younger moviegoers. Only 32 percent of its audience was under the age of 25.

In second place with $23.5 million was Fox’s Alvin and the Chipmunks: Chipwrecked. Like Sherlock, that represents a much worse opening than previous installments. The first movie, 2007′s Alvin and the Chipmunks, started out with $44.3 million, while the 2009 Squeakquel collected $48.9 million. The G-rated threequel earned a “B+” from CinemaScore audiences, with those under 18 years of age (43 percent of the audience) handing the movie a solid “A.”

It’s hard to know whether Chipwrecked‘s soft debut may spell the end for the poorly reviewed CGI rodent franchise. The film cost a relatively modest $80 million to produce and could hold up well during the holiday season as families look for kid-friendly entertainment options. Ultimately, it may come down to the movie’s overseas performance.

While the chipmunk trio might not be singing a happy tune this weekend, Tom Cruise most definitely is. His Mission: Impossible — Ghost Protocol, the fourth entry in the action series, grossed $13 million from just 425 IMAX and large-format theaters. (That figure rises to $13.6 million if you include Thursday evening showings.)

In advance of Ghost Protocol‘s wide release on Wednesday, Paramount decided to open the film early at large-screen locations as a way to build buzz and show off the 30 minutes of footage that director Brad Bird shot with IMAX cameras.

Mission accomplished. The $145 million movie averaged a towering $31,000 per theater and scored IMAX’s largest December opening ($11 million), topping TRON: Legacy ($10.5 million) and Avatar ($9.5 million). Also helping Ghost Protocol to a small degree was the six-minute The Dark Knight Rises prologue, which played in front of the film at 42 IMAX locations.
Jason Reitman’s Young Adult expanded from eight to 986 theaters, but could only muster $3.7 million. Despite strong reviews and a Golden Globe-nominated performance by Charlize Theron, the R-rated comedy averaged just $3,700 per location — or about 60 percent of what Chipwrecked earned at each theater.

In limited release, the silent dramedy The Artist, fresh off of six Golden Globe nominations, continued its solid but not spectacular performance by grossing $287,000 at 17 theaters. The spy thriller Tinker Tailor Soldier Spy expanded to 16 theaters and uncovered an impressive $452,000. And the Roman Polanski drama Carnage, an adaptation of Yasmina Reza’s Tony-winning play, opened to $85,700 at five locations for an okay $17,140 per-theater average.

1. Sherlock Holmes: A Game of Shadows — $40.0 mil
2. Alvin and the Chipmunks: Chipwrecked — $23.5 mil
3. Mission: Impossible — Ghost Protocol — $13.0 mil
4. New Year’s Eve — $7.4 mil
5. The Sitter — $4.4 mil