UEFA has charged Legia Warsaw over a banner criticising the Polish club's controversial exit from the Champions League.
Legia were eliminated from the Champions League third qualifying round for fielding a suspended player during the final minutes of a 6-1 aggregate win over Celtic.
UEFA awarded the Scottish side a 3-0 second-leg win that saw the Bhoys advance in Legia's place. Both UEFA and the Court of Arbitration for Sport denied Legia's appeals to be reinstated, but the latter is to consider the club's request for compensation from UEFA for lost earnings.
Legia supporters protested their side's elimination by displaying a large image of a pig imposed on a UEFA badge and the slogan "Because Football Doesn't Matter, Money Does."
The banner, surrounded by lit flares, was shown before Legia's Europa League playoff victory against Aktobe of Kazakhstan last Thursday.
UEFA said its disciplinary panel will judge the case on Thursday. Potential sanctions could be applied when Legia opens their Europa League group programme at home to Lokeren on Sept. 18.
If action is taken, it would mark Legia's third UEFA punishment in four seasons.
UEFA sanctioned fans' racist behaviour by closing a section of Legia's stadium at a Champions League playoff last season.
At a home Europa League match against Hapoel Tel Aviv three years ago, fans displayed a "Jihad Legia" banner in Arabic-style script across one end of the stadium.