Quavo and Offset Get into Fight Backstage at Grammys Over Takeoff Tribute

There's clearly still serious bad blood between Migos' rappers Quavo and Offset following the death of Takeoff ... and those emotions boiled over backstage at the Grammys into a physical fight.

Sources at the show tell us just before Quavo took the stage to perform his song "Without You" as a tribute to Takeoff during the "In Memoriam" segment of the show, he and Offset got into a physical fight and had to be pulled apart.

As for what led to it -- we're told The Grammys had asked Offset to be a part of the tribute, but Quavo refused to let him take part. We're told Quavo blocked Offset from joining him on stage ... leading to the melee.

Our Offset sources say it was Quavo who started the fight.

We should note -- Quavo and Takeoff were extremely close at the time of Takeoff's murder -- Offset was still hanging out with Takeoff separately, but the trio wasn't hanging out as a unit. Quavo's "Without You" was a song he specifically wrote for Takeoff.