Studios have rushed out a glut of movies before 31 December to make them eligible for the 2003 Academy Awards.
Industry watchers say the films are released as late as possible to keep them fresh in the minds of Academy voters ahead of the 11 February nominations.
The Oscars will be presented in Hollywood on 23 March.
Leading the list of high-profile movies appearing this weekend was the musical Chicago starring Catherine Zeta Jones, Richard Gere and Renee Zellweger.
The film, which opened to rave reviews, has received eight Golden Globe nominations and is being widely tipped for Oscar success.
The lavish adaptation of choreographer Bob Fosse's 1975 Broadway show is being heralded as the most ambitious musical since Evita.
Another much-fancied title making its debut was The Hours, adapted from a Pulitzer prize-winning novel based on the life and work of novelist Virginia Woolf.
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It's going to be a very confusing and very crowded Oscars season
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Tim Gray, Variety Daily
It stars Meryl Streep, Nicole Kidman and Julianne Moore as three women facing huge personal challenges over nearly 80 years of the 20th century.
"This film is definitely one of the ones to be most closely watched as an Oscars favourite," said Tim Gray, of the Variety Daily trade newspaper.
Prestigious
Also on release was Polish-born director Roman Polanski's film The Pianist, telling the story of a wartime musician who escaped from Nazi concentration camps.
The film won the prestigious Palme d'Or award at this year's Cannes Film Festival.
Other debuts included a new version of Charles Dickens' Nicholas Nickleby starring Christopher Plummer, Jim Broadbent, Jamie Bell and Edward Fox.
Oscar favourite The Lord of the Rings: The Two Towers is still cleaning up at the US box office following its release last week.
Critics and pundits are at odds over which films have the best chance of an Academy Award.
Variety's Tim Gray said: "It's going to be a very confusing and very crowded Oscars season."