The ATP is reviewing an accusation by tennis player Donald Young that fellow American Ryan Harrison used racially inappropriate language during a heated exchange at the New York Open on Monday night.
"The ATP takes any allegations of racial prejudice extremely seriously," the organization said in a statement. "A further review of all video and audio recording from the match will take place as this matter is investigated further."
After the match against Harrison, Young took to social media to say he was "shocked and disappointed ... to hear you tell me how you really feel about me as a black tennis player."
Harrison also took to social media after Young's post, saying the "accusations made by Donald Young tonight following our match are absolutely untrue."
Neither player would reveal exactly what was said.
The incident occurred during the New York Open, won by Harrison 6-3, 7-6 (4).
During a changeover, Harrison said something to the umpire, then looked in Young's direction. After Harrison sat down, he and Young exchanged terse words, and then both players approached each other. The chair umpire stepped down, had the players go back to their respective recovery zones and then carried on a discussion with Harrison while Young just shook his head.
After the match, Young reportedly refused a handshake by Harrison, and the two again exchanged words.
"We both started at a very young age on Tour, and we've had pressure and expectations on ourselves for a long time," Harrison told reporters after the match. "I've been very fortunate to have fought through a lot of the adversity. Donald is trying to fight through the adversity, trying to break back into where he wants to be.
"If that happened on a football field, everyone would laugh and say '15-yard penalty' and move on. You move forward and try to take it in stride. At the end of the day, you see everybody, you like everybody and you want to be friends and friendly with everybody, but everybody out here I compete against, even the ones I like, they are the ones trying to take away my livelihood. I have to do what I can to get through, and I was proud of myself for doing that."
The Associated Press contributed to this report.