Wales have lodged a third and final appeal in their attempts to have Russia kicked out of the European Championship.
The Football Association of Wales have been waging a battle to have the Russian side thrown out of Euro 2004 following Yegor Titov's positive drugs test.
Titov failed the test after the first leg of Wales' play-off in Moscow, which finished 0-0.
Wales want the result of the second leg, which Russia won 1-0, to be awarded 3-0 in their favour and have already lost two appeals in their bid to alter the scoreline.
They have now submitted an appeal to the Court of Arbitration for Sport in a final throw of the dice to claim a place in Portugal.
Mark Hughes' side lost the second leg, in which Titov played, in Cardiff 1-0 and will be anxious for the verdict to finally fall in their favour.
Chief executive of the FAW, David Collins, is optimistic the decision by the court will result in Wales taking Russia's spot at Euro 2004.
"We are working hard putting all of our written submissions together before the deadline, which is tomorrow evening," said Collins on Sky Sports News.
"Uefa then have 10 days to respond, so hopefully with the importance of the case, if we are allowed to have a full hearing they will hold it very quickly in May.
"We hope in the first instance Uefa will support the appeal to CAS in that they will allow it to go to the jurisdiction of the Court of Arbitration and then we test the case before the three arbiters."
"We feel when a player is on international duty that a player is representative of a national association.
"Titov was still under the influence of the drug when Russia and Wales played in Cardiff. We believe that should have given Wales the game by default, or at least made the match be replayed.
"Uefa did not support that at the appeals process... and that has given rise to this appeal to CAS.
"We had the help of an expert scientist from Canada, who was able to furnish us with evidence that we believed proved that the drug was still in Titov's system when he played in Cardiff, four days after he tested positive following the Moscow game.
"On that basis we believe that should have made Russia ineligible to compete in Euro 2004."