Less than 24 hours before Celtic fly out to Slovenia for their first leg against Maribor, the Court of Arbitration for Sport (CAS) rejected the Polish champions' appeal to be provisionally reinstated in Europe's premier competition.
The Swiss-based court will hear more detailed legal arguments from Legia, but the Poles are now looking for compensation and what they describe as "justice for football" to make sure that no other teams face similar sanctions for mistakenly fielding a suspended player.
In Legia's case, Bartosz Bereszynski came on in the 86th minute of their 2-0 second-leg win at Murrayfield, turning a 6-1 aggregate victory into an away-goals defeat after UEFA acted on its rules that clubs forfeit games for fielding ineligible players.
The Poles were already resigned to playing in the Europa League before the decision was announced and now travel to Kazakhstan to face Aktobe in a bid to qualify for the group stages of that competition.
Legia were previously angered by UEFA's refusal to sanction a fast-track CAS hearing after the European governing body's appeals body upheld its disciplinary panel's ruling that Celtic be awarded a 3-0 second-leg win over the Polish side.
Legia Warsaw chairman Dariusz Mioduski has vowed to continue the legal action in order to force UEFA to change its rules to make sure no other club was subjected to such measures.