UEFA is set to investigate with Zlatan Ibrahimovic over an "alleged financial interest in a betting company".
According to reports in his native Sweden, the AC Milan striker, 39, has violated rules after becoming a partner in a betting company.
Uefa's disciplinary regulations state players should not have a financial interest in betting.
Last week, he extended his contract with the Italian club that will run until after his 40th birthday.
"A Uefa ethics and disciplinary inspector has today been appointed to conduct a disciplinary investigation regarding a potential violation of the Uefa disciplinary regulations by Mr Zlatan Ibrahimovic for having an alleged financial interest in a betting company," a Uefa statement said.
The former Manchester United striker has scored 17 goals in 25 appearances in all competitions this season.