The Screen Actors Guild, the Hollywood union that is one of the most reliable early predictors of the Oscars, will announce the nominees for its awards in a ceremony starting at 5:50 a.m. Pacific on Wednesday morning.

Here's a breakdown of the top film categories.

1) Best performance by a cast ensemble: Is it a year for laughter or tears?

SAG's prize for performance by a cast in a motion picture -- chosen by 2,200 nominating voters -- often forecasts the Academy Awards' best picture race. This year large casts from films such as "12 Years a Slave," "Saving Mr. Banks," "American Hustle" and "The Wolf of Wall Street" will duke it out for the guild's affections. While many of those casts are likely to be nominated, will SAG ultimately reward a crowd-pleaser, a la "The Wolf of Wall Street" and "Saving Mr. Banks," or a more somber drama like "12 Years a Slave"?

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2) Best performance by a male actor in a leading role: Will this category belong to the veterans?

With 77-year-old Bruce Dern ("Nebraska") and 77-year-old Robert Redford ("All Is Lost") strong contenders, it's an impressive year for septuagenarian performances. Chiwetel Ejiofor ("12 Years a Slave"), Matthew McConaughey ("Dallas Buyers Club"), Tom Hanks ("Captain Phillips") and Oscar Isaac ("Inside Llewyn Davis") will likely also be in the mix when nominations are announced.

3) Best performance by a female actor in a leading role: Which familiar faces will we see?

Most of the potential nominees in this category are well known to awards voters -- previous Oscar winners like Cate Blanchett ("Blue Jasmine"), Sandra Bullock ("Gravity"), Emma Thompson ("Saving Mr. Banks"), Meryl Streep ("August: Osage County") and Judi Dench ("Philomena"). The question for Wednesday: Will SAG skip a familiar face in favor of a newcomer like Brie Larson ("Short Term 12") or Adele Exarchopoulus ("Blue Is the Warmest Color")?

4) Best performance by a male actor in a supporting role: Might sentiment steer the day?

This category gives voters an opportunity to acknowledge James Gandolfini, who died in June before audiences saw his tender performance in the romantic comedy "Enough Said." Other possible contenders in the field include Jared Leto ("Dallas Buyers Club"), Michael Fassbender ("12 Years a Slave"), Jake Gyllenhaal ("Prisoners"), Daniel Bruhl ("Rush") and Hanks again, this time as Walt Disney in "Saving Mr. Banks."

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5) Best performance by a female actor in a supporting role: Who said it best?

While Lupita Nyong'o is a favorite in this category for her emotionally intense performance in "12 Years a Slave," several of the other women likely to be contending delivered sharp-tongued dialogue in their films, including Oprah Winfrey ("The Butler"), Jennifer Lawrence ("American Hustle"), June Squibb ("Nebraska"), Margo Martindale ("August: Osage County") and Julia Roberts ("August: Osage County").

The nominations will be announced at the Pacific Design Center in Los Angeles, starting with stunt performer categories at 5:50 a.m. Wednesday and the main nominations at 6 a.m. They can be viewed live on tbs.com and, starting at 6 a.m., on TNT.

The 20th Screen Actors Guild Awards will be simulcast live on TNT and TBS on Saturday, Jan. 18, 2014, at 5 p.m. PST from L.A.'s Shrine Exposition Center.

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