The ATP is reviewing Donald Young's accusations that Ryan Harrison used racially inappropriate language during the Americans' heated exchange in their opening-round match at the New York Open.
Harrison defeated Young 6-3 7-6 (7-4) on Monday.
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At one point during a changeover the two appeared to be arguing and the chair umpire moved in between the players in an attempt to calm the situation.
Young posted on Twitter after the match : "I'm shocked and disappointed, Ryan Harrison, to hear you tell me how you really feel about me as a black tennis player in the middle of our NY match."
Harrison responded on Twitter that the allegations were "absolutely untrue" and audio from the match would "clear me."
"The ATP takes any allegations of racial prejudice extremely seriously," the organisation 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."
It hasn't been a great few days for American tennis, with Texas A&M freshman Patrick Kypson appearing to spit in his hand before attempting his postgame handshake with Ohio State freshman J.J. Wolf earlier this week.
Kypson was disciplined for his actions and did not appear in Sunday’s match against No. 24 Texas Tech.