The ATP says it 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.
"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."
Harrison defeated Young 6-3 7-6 (7-4) on Monday. 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."