Rihanna was asked to headline next year's Super Bowl halftime show but turned it down in support of Colin Kaepernick, according to US media.
Kaepernick was the first in a series of National Football League (NFL) stars to kneel during the US national anthem before matches, with players saying they wanted to draw attention to racism and police brutality.
He has not played in the NFL since early 2017 and is suing the organisation – claiming team owners have frozen him out to due to his activism.
Reports say Rihanna was first choice to perform at next year's Super Bowl halftime show, which is broadcast on the CBS network, but the singer declined to take part due the issue.
"Rihanna was the frontrunner for next year's super bowl halftime show," Entertainment Tonight reported, quoting an anonymous source.
"CBS and the NFL reached out to Rihanna first, who after thinking about the offer, decided to pass due to the NFL and the situation regarding players kneeling."
According to the source, the singer "stands with the players and Colin Kaepernick".
The reports first appeared in US Weekly, which quoted a source saying that organisers for the game "really wanted Rihanna to be next year's performer in Atlanta".
Entertainment Tonight says Pink was also approached for the gig, but passed as negotiations went on for too long.
Maroon 5 have been confirmed as headliners for the show, which will take place on 3 February in Atlanta, Georgia.
Kaepernick is currently the face of a Nike campaign marking 30 years of the "Just Do It" slogan.
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Adverts unveiled just days before the start of the 2018 NFL season show a portrait of the sports star with the slogan: "Believe in something. Even it means sacrificing everything."
The Super Bowl game is the climax to the American football season, watched by millions across the world.