* Miniseries "Mildred Pierce" leads with 21 nominations
* Close races in best drama series, drama acting (Updates with red carpet arrivals)
By Jill Serjeant
LOS ANGELES, Sept 18 (Reuters) - Television's "Mad Men" went to the Primetime Emmy Awards on Sunday, hoping to fend off the Prohibition-era gangsters of "Boardwalk Empire" and win a fourth straight victory at the industry's top honors.
"Glee" star Chris Colfer, Christina Hendricks of "Mad Men" and Joel McHale of "Community" were among early arrivals on a red carpet packed with diamond jewelry and glorious gowns in shades of coral and pink.
More than 20 Emmys will be handed out in the live telecast on the Fox network hosted by "Glee" star Jane Lynch, who could find herself accepting an early award for her supporting actress role as a sarcastic cheerleading coach on the hit musical comedy.
But all eyes will be on the top prizes -- for best comedy and drama series to be handed out at the end of the three-hour ceremony -- and some major upsets could be in store, especially in the acting categories.
ABC mockumentary and 2010 Emmy comedy series winner "Modern Family" goes into Sunday's awards with 17 nominations, including acting mentions for all six of its stars.
That puts it in a commanding position for a repeat victory over rivals "Glee," "The Office," "Parks and Recreation" and "The Big Bang Theory."
The contest for best drama is much closer. HBO's lavish new show "Boardwalk Empire," with 18 nominations, has already taken Golden Globe and Screen Actor's Guild trophies and is regarded as a major contender, despite the 19 nods to "Mad Men," the 1960s advertising drama on AMC.
Medieval fantasy series "Game of Thrones," which proved a surprise success for HBO, has an army of fans, while CBS lawyer show "The Good Wife" starring Julianna Margulies topped an Xfinity TV poll on Facebook as favorite drama. "Dexter" and "Friday Night Lights" make up the other drama contenders.
ACTORS & ACTRESSES
Margulies also is the front-runner for best dramatic actress, along with Elisabeth Moss, who plays the quiet but feisty young Peggy Olson of "Mad Men."
"It is such a great showcase for Moss. It is quite a contest. I think Margulies will win, but it is very close," said Tom O'Neil of awards website TheEnvelope.com.
Jon Hamm, who plays suave but enigmatic Don Draper in "Mad Men," also is hoping to clinch his first Emmy this year.
"Hamm is the lead star of this Emmy-anointed show who has never won. But he has got to watch out for Steve Buscemi on 'Boardwalk Empire,'" said O'Neil.
The HBO miniseries "Mildred Pierce" has a leading 21 nominations and is expected to deliver an acting Emmy for its star, British actress Kate Winslet.
But surprises could be in store for Emmy newcomer Melissa McCarthy of comedy "Mike & Molly," who also stole the show in the summer movie "Bridesmaids".
"She is an outstanding comedic actress. She was also so funny and winning in 'Bridesmaids' and I think audiences got her and she won new fans," said Todd Gold, managing editor of Xfinity TV.
The popular reality competition slot is also a cliffhanger. Victory may finally be at hand for America's most-watched show "American Idol," but "Dancing with the Stars" or "So You Think You Can Dance" could waltz away with the Emmy. (Editing by Eric Walsh)