FIFA president Sepp Blatter and UEFA boss Michel Platini are facing lengthy bans if they're found guilty of corruption.
The duo, who are the two of the most powerful figures in world football, are both currently serving 90-day suspensions over a £1.3M payment Blatter made to Platini in 2011.
FIFA's ethics judge has opened cases against them.
In a statement on the FIFA website, it says: "The adjudicatory chamber of the independent Ethics Committee chaired by Hans-Joachim Eckert has today opened formal adjudicatory proceedings against Joseph S. Blatter and Michel Platini based on the final reports submitted by the investigatory chamber.
"The adjudicatory chamber has studied the reports carefully and decided to institute formal proceedings against the two officials. For reasons linked to privacy rights and the presumption of innocence until proven guilty, the adjudicatory chamber will not publish details of the sanctions requested by the investigatory chamber in its final reports.
"In the course of the proceedings, both parties will be invited to submit positions including any evidence with regard to the final reports of the investigatory chamber (art. 70 par. 2 of the FIFA Code of Ethics) and they may request a hearing (art. 74 par. 2 of the FCE). The adjudicatory chamber intends to come to a decision in both cases during the month of December."
If one or both men are found guilty, they could face seven-year bans from football.
Earlier, Blatter told a Swiss TV station that he was "close to dying" after suffering a "small emotional breakdown" recently.
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