FC Utrecht appealed to the CAS after Olympique Lyon were found to have fielded an unregistered player in their UEFA Europa League meeting on September 25th, which Lyon won 1-0. Algerian winger Rachid Ghezzal was brought on for Adam Karabec in the 65th minute, despite not being registered by Lyon before the start of the UEFA Europa League season.
After UEFA ignored the matter, Utrecht appealed to the CAS, which has now ordered UEFA to open an investigation after ruling that UEFA wrongfully failed to initiate disciplinary proceedings.
"FC Utrecht expect UEFA to implement the imposed obligation carefully and expeditiously. The club will continue to monitor developments closely and will communicate as soon as there is reason to do so," the club said in an official statement.
It is unknown whether UEFA will discipline Lyon, and if so, to what extent.