Rapper Childish Gambino's "This is America", about police brutality and racism, won the first big award - song of the year - as well as best music video, and best rap performance.
For the second consecutive year, black hip-hop artists are leading the pack - but observers are still wondering if nominations success can translate into big wins.
The lead up to this year's Grammys hasn't been completely smooth though.
Women artists scored nominations in all of the top categories, after being largely muted a year ago: rapper Cardi B, pop diva Lady Gaga, pop futurist Janelle Monae and folk rocker Brandi Carlile are among the frontrunners.
"It was when my creativity & self expression was stifled by you, that i decided not to attend. i hope the show is exactly what you want it to be and more", she continued.
The singer, who sent the tweets just hours before the highly anticipated release of her album Thank U, Next, is up for two awards this year: best pop solo performance for God Is a Woman, and best pop vocal album for Sweetener.
As has become the case in recent years, the Grammys started handing out awards before the awards ceremony on Sunday night, leaving Gaga awash in emotions and tears even as she was still getting ready for the big event.
Gaga told the crowd: "They said I was weird, that my look, that my choices, that my sound wouldn't work". Instead, it was 100 percent Gaga - and singer Gaga, not actress Gaga - up on that stage, back to her old tricks of belting out lyrics amid leg kicks, insane faces and whipping her hair back and forth.
Ariana Grande has said no thanks to the Grammy Awards.
The Grammys have also struggled with gender inequality, an issue that came to its head past year.
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To help combat the Grammys' much-discussed diversity problem, the Recording Academy expanded the major categories to eight nominees each - so now that the field is wider than ever, expect some upsets.
Gaga, Carlile, Monae, Cardi B and Musgraves are all due to take the stage.
Some complained that a black artist should be involved in the tribute, while others said stronger vocalists should perform over Lopez. Yolanda Adams, Fantasia and Andra Day will honour the late Aretha Franklin with a performance.