The music world gathers on Sunday for the Grammys with the top awards a choice between a new, edgier Beyonce and the time-tested ballads of Adele.

The televised bash from Los Angeles could also have political fireworks as many artists are outspoken critics of United States President Donald Trump.

But the enduring picture from the Grammys may turn out to be Beyonce, who is expected to make her first public appearance since revealing that she is pregnant with twins.

Beyonce leads the Grammys with nine nominations and could win the most prestigious awards for the first time - Album of the Year for Lemonade and Record of the Year for her song Formation.

Lemonade, which Beyonce intertwined with a film, marked a new direction for the pop superstar as she dabbled in hip-hop, hard rock and even country.

Formation was the most politically upfront song of Beyonce's career with a video rallying behind the Black Lives Matter movement, including an image of police officers surrendering as if under arrest.

Beyonce faces competition in the main categories from Adele, who proved her enduring, massive commercial popularity by sticking to her style of wrenching ballads.

The English singer is nominated for her ubiquitous song Hello and her album 25, which has been the world's top-seller since her 21, which also triumphed at the Grammys.

Adele is scheduled to sing at the Grammys - a year after her performance was marred by a falling microphone, which hit the piano and caused her voice to veer jarringly out of tune.

Other artists who stand a chance to win the most Grammys include Toronto rapper Drake, R&B superstar Rihanna and the hip-hop celebrity fixture Kanye West.

Katy Perry, back from a short hiatus in which she recorded new music, will use the global television platform to perform Chained to the Rhythm, her retro disco-inspired new single.

Perry - who with 95 million followers is the most popular person on Twitter - released the song on Friday after a unique social media campaign in which she sent fans around the world hunting for disco balls that held recordings of the single.

Lady Gaga - who a week ago performed before more than 117 million television viewers at the Super Bowl halftime show - is set for one of the more unlikely Grammy collaborations as she takes the stage with Metallica.

The event will also feature tributes to two pop icons who died in the past year - Prince and George Michael.