More than 1,000 Everton fans have had their tickets cancelled for the Uefa Cup match against Nuremberg in Germany on Thursday.
Nurnberg had openly sold tickets directly to Everton supporters over the internet which would have seen fans from both clubs sitting together.
Now on Uefa instruction, after they classified the game a risk' match, those tickets have been cancelled because clubs are not allowed to enter into such transactions.
Fans must buy from the official allocation - believed to be 3,000 - that Everton have had for a secure part of the stadium.
Everton spokesman Ian Ross said: "We would never recommend that supporters get tickets from the host club, there are concerns when they do that, there are potential pitfalls.
"Those who have bought them are now being told they cannot use them. We got the biggest allocation we possibly could, but we could have sold them five times over."