According to TMZ, tensions boiled over between Quavo and Offset backstage at the Grammys just moments before Quavo took the stage to pay tribute to Takeoff.

Sources told TMZ that Offset and Quavo had to be pulled apart during an altercation that started after Quavo refused to let Offset join him onstage for the performance of "Without You." Quavo wrote the song as a tribute to Takeoff after his tragic passing, and Offset wasn't featured on the song. 

However, the Grammys reportedly asked Offset to join Quavo for the performance, but Quavo blocked Offset from getting on the stage, which led to the fight. More details to come. 

Source: TMZ