FC Sion's suspension from participation in this season's Europa League has been upheld by UEFA, meaning that Celtic are free to take on Atletico Madrid this Thursday in the opening match of the group stage.
Swiss side Sion defeated Celtic 3-1 on aggregate during the qualifying rounds, but they were later excluded from the competition after it was revealed that they had included five ineligible players in their squad.
Sion appealed the decision, but UEFA have decided to stand by their original verdict, paving the way for Neil Lennon's Celtic to re-enter the competition.
"The UEFA Appeals Body today rejected FC Sion's appeal against their expulsion from the group stages of this season's Europa League," read a statement on Celtic's official website.
"Celtic were reinstated to the competition, and will take on Atletico Madrid, Udinese and Rennes.
"Clearly, Celtic are pleased with the decision."
Sion could still opt to take the case to the Court of Arbitration for Sport.
