Fans travelling from Wales by car to their team's Euro 2016 quarter-final against Belgium in Lille later on Friday fear missing the game because of long delays at the Eurotunnel.
Eurotunnel Le Shuttle tweeted that passengers faced departure-time delays of some five hours in Folkestone, as a technical problem involving a train stopped in the tunnel created havoc with the timetable and led to cancellations and delays.
The match in Lille, which lies some 100 kilometres from the shuttle terminus in Calais, kicks off at 1900 GMT. Eurotunnel said it has added three extra trains but that delays would continue all day.
Fans with tickets for the game told the BBC of "chaotic scenes" and of the situation being "a nightmare," with long delays also before check-in. Some even asked for a delay of the kick-off time but ruling body UEFA was quoted as saying that the majority of fans will be there for the game.
Wales manager Chris Coleman said in a message on the Facebook page of the Welsh FA he and the team were aware of the problem.
"We know a lot of people have gone the extra mile to come over and your efforts at this frustrating time is very much appreciated. We know that we have your full support for tonight's game," he said.
Friday's game is the biggest for Welsh football since a 1958 World Cup quarter-final against Brazil which they lost 1-0.
Meanwhile, regular Eurostar trains from London to Paris, which stop in Lille, were running largely on time.