Image Credit: Jaimie TruebloodSony has football’s big game all figured out. For the eighth year since 2001, the studio topped Super Bowl weekend, this time with the PG-13 college thriller The Roommate, which debuted to $15.6 million, according to studio estimates. The Single White Female protégé, about a college freshman (Minka Kelly) and her mentally unstable dorm-mate (Leighton Meester), drew a young, female audience: 65 percent was female, and 61 percent was less than 21 years old. With a “B-” rating from CinemaScore moviegoers, though, The Roommate will likely follow in its genre’s footsteps and quickly tumble starting next weekend.

Sanctum, however, better not sink as fast, as the $30 million cave-diving thriller started its expedition with an underwhelming $9.2 million. That figure isn’t as disappointing when you take into account that Universal and Relativity Media paid only $12 million to acquire the film, but when the name James Cameron is linked to a project, one expects more intimidating box-office muscle. Cameron produced the R-rated film, which utilized the same 3-D technology the filmmaker had developed for Avatar. What was expected to be a movie that skewed heavily toward men actually attracted a crowd that was 53 percent female. The audience was on the older side, too, with 65 percent at least 30 years old. But CinemaScore moviegoers gave Sanctum an unpleasant “C+” grade.

In third was the Natalie Portman-Ashton Kutcher romantic comedy No Strings Attached, which fell a slim 37 percent for $8.4 million. The King’s Speech was right behind in fourth place, earning $8.3 million — a 25 percent decline — to bring its cumulative gross to $84.1 million. In fifth, The Green Hornet continued to hold up well for a superhero film, dropping 46 percent for $6.1 million. The Seth Rogen action comedy has so far tallied $87.2 million, and is on pace to become 2011’s first $100 million picture. Last week’s winner, The Rite, will be lucky to reach a third of that. The Anthony Hopkins horror film descended 62 percent this weekend for $5.6 million. Its two-week total stands at $23.7 million.

In limited release, Waiting for Forever may have to do just that to find its audience. The Rachel Bilson-Tom Sturridge romance opened to a paltry $10,200 from three theaters. Check back next week as four new movies — the Roman action film The Eagle, the animated Gnomeo and Juliet, the Adam Sandler-Jennifer Aniston romantic comedy Just Go With It, and the Canadian spectacle Justin Bieber: Never Say Never — battle to the death for your attention.

1. The Roommate — $15.6 mil

2. Sanctum — $9.2 mil

3. No Strings Attached — $8.4 mil

4. The King’s Speech — $8.3 mil

5. The Green Hornet — $6.1 mil

6. The Rite — $5.6 mil