Celtic should not book their flights or hotels for the game against Athletico Madrid at the moment. As ever, when there is scope for an appeal, one will be made. Celtic cannot take it for granted that they will be playing in the group stages of the Europa League just yet. Sion do not intend to roll over and accept UEFA's decision to give Celtic the Europa League group place the Swiss side thought they had won. They are confident that they will win their case after being kicked out of the completion, after beating Celtic over two play-off legs, to The Swiss side won 3-1 on aggregate but were thrown out by UEFA for fielding players deemed by FIFA to be ineligible due to a transfer ban. Sion point to a Swiss court decision which had ruled in their favour regarding the players eligibility for the games. Last Friday, UEFA announced that the tie had been awarded to Celtic, on 3-0, 3-0 basis, and the Parkhead side were reinstated in Sion's place in the group which includes Atletico Madrid, Udinese and Rennes. The first game involving neither Sion or Celtic isscheduled to take place in Spain on 15 September. Sion president Christian Constantin remains confident of success in court and has reportedly booked flights and hotels in Madrid. Sion's lawyer Alexandre Zen-Ruffinen insists Constantin's club will win their case as UEFA defied the decision by the Swiss court to allow the players to take part against Celtic. He said: "We received the decision of UEFA on Monday morning. Now we must obviously consider the document and then spend hours and hours to find a way to attack it. Ultimately we will succeed because their position is untenable. By rights UEFA have to comply with the laws of its own country. But by refusing to consider the decision of a Swiss judge, they did just the opposite. Specifically, those players entered the civil justice system to qualify, so it is not acceptable. The next few days are vital because the appeal decision must be known by next Monday so we can play the game in good condition." While the legal battle goes on, Atletico Madrid are in the dark over how to prepare for next week's game. A spokesman said: "Right now we don't know who we are going to face in the Europa League, so we can't plan anything."