The suit, filed last week in federal court in Brooklyn against the USTA, contends Anthony Nimmons, who started umpiring in 1994, was demoted and ultimately fired for speaking up about a racist environment in the world of tennis officiating. It seeks unspecified damages.

The USTA "strictly prohibits discrimination and retaliation in its workplace," organization spokesman Chris Widmaier said Wednesday.

"We categorically deny the claims of Mr. Nimmons and will vigorously defend the suit," he said.

Among the incidents Nimmons says he reported to the nation's governing body for professional tennis was an encounter with a white umpire at the 2013 US Open in New York City who allegedly taunted him by by saying, "Hey Tony, if you were a hungry monkey and I told you there was a watermelon in the tree -- go get it! -- how would you feel?" At a lower-level tournament in Dallas in 2012, he says another white umpire yelled, "Tony, you should go back to the ghetto!"

As a result of his complaints, "I was stripped of my work -- including my diversity duties and travel to the Grand Slams tennis tournaments (e.g., the Australian Open, French Open-Roland Garros, Wimbledon and the U.S. Open), to promote diversity, and where I had otherwise officiated with approval for decades," Nimmons said in a statement included in the suit.

He added: "I love tennis and want my job back at the USTA."

The suit says an Equal Employment Opportunity Commission investigation found there was "credible evidence" that Nimmons was discriminated against and issued a "right to sue" letter on his behalf.