ET has your box office scoop!

JIM CARREY pulled another box office hit out of his hat, as his animated 'Horton Hears a Who!' topped the box office with this year's biggest opening so far: $45.1 million, according to preliminary studio estimates.

Carrey, in his second DR. SEUSS film (he also starred in 'How the Grinch Stole Christmas'), plays Horton the elephant, who hears voices coming from a speck of dust. Horton soon discovers, to his amazement, that a planet containing a village called "Who-ville" is located in the infinitesimal grain of dust and it's up to him to protect the people who live there. STEVE CARELL voices Mayor of Who-ville, while DANE COOK, SETH ROGEN, CAROL BURNETT, JAIME PRESSLY, ISLA FISHER, JONAH HILL ('Superbad'), WILL ARNETT ("Arrested Development") and AMY POEHLER ("Saturday Night Live") also provide voices.

'10,000 B.C.' dropped to second place with $16.4 million. The ROLAND EMMERICH film follows a mammoth hunter as he goes on a quest that could make or break his tribe. STEVEN STRAIT and CAMILLA BELLE co-star.

Premiering in third place was 'Never Back Down' with $8.6 million. The mixed martial arts flick follows a hot-headed teen (SEAN FARIS) as he joins an underground fight club and gets a veteran head-cracker ('Blood Diamond's DJIMON HOUNSOU) to mentor him.

'College Road Trip' dropped to fourth with $7.9 million. The comedy about a young woman (RAVEN-SYMONE) traveling the country in search of a college co-stars MARTIN LAWRENCE as her overprotective cop dad and also features "The Insider"'s very own temporary co-host, DONNY OSMOND.

Rounding out the top five was 'Vantage Point,' which made another $5.4 million. The political thriller stars MATTHEW FOX, DENNIS QUAID, FOREST WHITAKER, WILLIAM HURT and SIGOURNEY WEAVER.