A Russian tennis player has been thrown out of a tennis tournament in the US because he questioned the impartiality of the umpire, given that both she and his opponent were black.

Daniil Medvedev, 20, was immediately disqualified from the Savannah Challenger - a competition that forms part of the ATP World Tour - on Thursday, after he “questioned the impartiality of the umpire, based on her race.”

Medvedev was playing Donald Young, a 26-year-old American, in the second round match.

Young is currently ranked 84th in the world, while Medvedev is 260th.

The Russian was losing 3-1 in the first set but, as he looked to regain his momentum, the umpire, Sandy French, called his forehand wide.

While he was walking back to the baseline, he uttered under his breath: “I know that you are friends. I am sure about it.”

Microphones on the ATP Tour’s live-streaming service picked up his words.

And at the end of the game, tournament supervisor Keith Crossland was called to the court by Ms French to discuss Medvedev’s behavior. After a lengthy discussion with Medvedev, Mr Crossland walked over to Ms French in the umpire’s chair and appeared to give his consent for the match to be handed to Young through an unsportsmanlike default against Medvedev.

Ms French announced the news to the crowd, who had no idea what was going on.

“Unsportsmanlike conduct. Default Medvedev,” she told the crowd through her chair umpire microphone. “Game. Set. Match. Young. 4-1. Default.”

The USTA later released a statement confirming Medvedev was disqualified for racist comments. 

Mike Cation, the match commentator, said he also never saw Medvedev do anything deserving of an unsportsmanlike default.

“I wish we’d picked up what Medvedev said because it must have been pretty bad,” he added.

The New York Times compared the incident to Lleyton Hewitt’s infamous comments during a second-round win against American James Blake at the 2001 US Open.

Hewitt appeared to complain that the line judge was giving special treatment to Blake, as both men were black.

“I’ve only been foot-faulted up one end. Look at him, look at him, look at him, mate,’’ said Hewitt. “Look at him and you tell me what the similarity is. Get him off the court. Look at what he’s done.”

Hewitt has always insisted that his call for the linesman to be moved had nothing to do with the colour of his skin. The linesman was changed and Hewitt was cleared by an International Tennis Federation investigation, which found there was no evidence to bring charges against the player for making a racial comment.