The Rev Al Sharpton has called on Russian authorities to put the fate of Brittney Griner above the concerns of "national boundaries".
Speaking in Chicago alongide the player's wife, Cherelle Griner, the veteran civil rights activist said Ms Griner was a "champion" whose talents were recognised internationally.
He said the 31-year Phoenix Mercury centre and two-time Olympic gold medalist had spent far too being detained in Russia and that it was time to bring her home.
"She didn't see Russian fans any different than American fans," Mr Sharpton said, a day after Ms Griner appeared in court where she pleaded guilty to drugs charges.
"She saw all of them as fans that deserve the right to see women play basketball. She did that and I hope that is what is considered, as we see what happens now that she's taken this stance."
Cherrele Griner thanked Mr Sharpton and the Women's National Basketball Association, for their support at this "gut wrenching time for my entire family".
She said she had spoken to President Joe Biden who had told her he had read and understood the letter that Ms Griner had sent to him.
"He did write her back and I was able to read the letter and it brought me so much joy as well as BG," she said, using the initials with which the world of basketball often uses when referring to her wife.
"I believe every word that she said to him, he understood, and he sees her as a person and he has not forgotten her, which was her biggest cry in her letter."
On Thursday, Ms Griner appeared at a court in Moscow where she pleaded guilty to a drugs charge. Her appearance followed her being stopped at Moscow's Sheremetyevo Airport in February, while returning to play for the Russian team UMMC Ekaterinburg.
Police said they found vape canisters containing cannabis oil in her luggage.
Speaking through an interpreter, Ms Griner pleaded guilty to the charge, but said she had intended to break the law. Rather, her offence, was one of "negligence".
Mr Sharpton said that again the backdrop of conflicts that take place around the world, "there ought to be those that can engage in work that goes beyond boundaries and differences".
"Sports and faith or not be confined to the boundaries of any nation or any belief. And no one has exemplified that more than Brittney Griner," he said.
"Brittney Griner has played all over the world, even when some would not go to Russia, she would go there and has been a global role model to show that there is no boundaries for those that want to engage in athletics."
Amid accusations from the US government and her supporters that Vladimir Putin is seeking to use the player as leverage against the West, Mr Sharpton said Griner should not suffer as a result of having taken a decision to play in Russia.
He said she had shown an example to people around the world by taking responsibility for the actions leveled at her.
He added: "She didn't see Russian fans any different than American fans. She saw all of them as fans that deserve the right to see women play basketball."
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