Atletico Madrid, Rennes, Celtic and Udinese, who might have to play extra games against the Swiss side, have asked the Court of Arbitration of Sport (CAS) to make Sion pay damages to them should they be readmitted.
Atletico spokesman Juan Jose Anaut told Reuters on Friday that the four clubs, who make up Europa League Group I, had made a joint petition to CAS, based in Lausanne, over the extra costs and inconvenience Sion's inclusion would cause.
Celtic took Sion's place in Group I but the civil court in Vaud canton issued an injunction ordering UEFA to reinstate the club.
"Like Rennes, Udinese and Celtic, Atletico feel directly affected by this ruling, which does not fit in with sporting regulations," Atletico lawyer Juan de Dios Crespo told the Spanish sports newspaper As.
"This would mean that we travelled all the way to Rennes in France and Udine in Italy for nothing," said Anaut. "We would also have to find more space in the calendar which is already full."
