LOS ANGELES: The music world gathers in Los Angeles on Sunday for the Grammys, with oddly-punctuated indie pop band fun. hoping to win big at the industry's top awards show -- as long as they keep their clothes on.

Elton John, Taylor Swift and Mumford & Sons are among a galaxy of stars to take the stage at the Staples Center -- albeit with a warning not to show too much flesh, be it breasts, nipples or the dreaded "buttock crack."

Others in the running for Grammys glory include rapper Frank Ocean, The Black Keys, Jack White, Kelly Clarkson and Gotye, while late Indian sitar guru Ravi Shankar is set to receive a posthumous lifetime achievement Grammy award.

But New York band fun. topped nominations announced in December, shortlisted in six categories including the key ones of best album ("Some Nights"), song ("We are Young"), record (for producers of "We are Young") and best new artist.

If they were to win all four, it would mark the first such achievement in more than 30 years, according to The New York Times.

Rap artist Frank Ocean also scored six nominations, including for best album (the critically acclaimed "Channel Orange"), record of the year ("Thinkin Bout You"), best new artist and best urban contemporary album.

Ocean caused a stir in the macho and sometimes homophobic realm of hip-hop when he revealed in a Tumblr blog prior to the release of "Channel Orange" that he had been involved in a gay relationship.

The Grammys are the premier music industry awards in the United States, with no fewer than 81 categories. Winners are determined by voting among members of the National Academy of Recording Arts and Sciences.

Also vying for best album are three-time Grammy winners The Black Keys for "El Camino," British rock-folk group Mumford & Sons for "Babel" and rocker Jack White for "Blunderbuss."

Record of the year contenders also include The Black Keys' "Lonely Boy," Kelly Clarkson's "Stronger (What Doesn't Kill You)," Gotye's "Somebody That I Used to Know" and Taylor Swift's "We Are Never Ever Getting Back Together."

Last year's Grammys were dominated by British soul songstress Adele, who collected six awards, including album of the year for "21" -- only the second woman in Grammy history to collect so many awards in a single go.

Nominated for best song this year were British balladeer Ed Sheeran's "The A Team," Miguel's "Adorn," Carly Rae Jepsen's "Call Me Maybe" and Clarkson's "Stronger," alongside "We Are Young."

Failing to get any nominations in major Grammy categories were veterans Bob Dylan, Bruce Springsteen and Lionel Richie, R&B diva Rihanna, teen idol Justin Bieber and Brit boy band One Direction.

In the Grammy show's traditional In Memoriam segment, Elton John will join fellow British stars Mumford & Sons and others in paying tribute to Levon Helm, the late drummer and singer with The Band.

The Grammys live telecast starts at 5:00 pm Sunday (0100 GMT) Monday and lasts three and a half hours.

On the eve of the show, a leaked letter from US television network CBS -- which broadcasts the Grammys live -- warned stars not to reveal too much skin on stage Sunday night.

"Please be sure that buttocks and female breasts are adequately covered... Thong-type costumes are problematic. Please avoid exposing bare flesh under curves of the buttocks and buttock crack," it said.

"Bare sides or under curvature of the breasts is also problematic. Please avoid sheer see-through clothing that could possibly expose female breast nipples."

Last year's show went ahead under a cloud, after singing legend Whitney Houston was found dead in her Beverly Hills hotel bathtub on the eve of the Grammys. Coroners concluded she possibly overdosed from drugs and alcohol.

On Saturday, 24 hours before the show, CBS will air an hour-long documentary about the star and the last-minute production scramble to take account of her death, entitled "The Grammys Will Go On: A Death in the Family."