England prop Joe Marler will face an independent World Rugby misconduct hearing for calling Wales forward Samson Lee "Gypsy boy".
Six Nations organisers had ruled Marler would not be punished for his comments made during a game on 12 March.
But World Rugby, which governs the international game, says his remarks "amount to misconduct and/or a breach" of its code of conduct.
The case will be heard "as soon as practically possible".
Marler apologised to Lee, who is from the Traveller community, at half-time during England's 25-21 win over Wales at Twickenham.
The Harlequins player was subsequently reprimanded by England head coach Eddie Jones, but the decision not to sanction him caused upset.
Campaigners from the Traveller community - and figures inside the sport - were critical of Marler for making the comment and called for a ban.
The Welsh Rugby Union was also disappointed with the outcome.
It released a statement saying: "We stand by our belief that there is no place for the use of racist language in sport."
Like Lee, Wales head coach Warren Gatland described the incident as "banter" but later apologised following criticism.
Meanwhile, Conor O'Shea, Marler's club coach at Harlequins, has leant his support to the under-fire forward.
"He is not in any way shape or form racist," O'Shea said. "He is an edgy person, he made a mistake and he apologised.
"Does he know that he has got a responsibility? Of course he does. Do we accept it? Of course we don't, but some of the vitriol that has been directed to him is tough for a 25-year old to take and he has to take it on the chin."