The Scottish Football Association has received referee Bobby Madden's report on Saturday's match between Celtic and Aberdeen, during which Aberdeen claim Shay Logan was racially abused.
Logan complained to Madden during the game that Celtic's Aleksandar Tonev had made a racist remark to him.
Celtic say that the Bulgarian winger insists the allegation is not true.
SFA compliance officer Vincent Lunny must now decide if there is sufficient evidence to issue a complaint.
The likelihood is he will have to try to gather further evidence and any complaint, should it come at all, would not be issued to Tonev until later this week.
The incident, said to have occurred early in the second half of the Premiership match at Celtic Park. will also have featured in Scottish Professional Football League delegate John Connelly's report.
Tonev and Logan were direct opponents for much of the match which Celtic won 2-1.
Logan also told his captain Mark Reynolds about the alleged incident and he too had a word with Madden.
Tonev was making a belated debut for the Scottish champions having signed on loan from Aston Villa in the summer, though injury delayed his bow.
Fraser Wishart, chief executive of PFA Scotland, said it would be "inappropriate to comment at this time" because the incident could result in an investigation by the SFA.
No official complaint was made to police regarding the allegation against Tonev. However, following media reports, police are aware of the alleged incident and are making enquiries into the circumstances.