Manchester United have been warned of a security scare ahead of its Champions League semi-final with AC Milan.
It is thought that trouble may break out at Wednesday night's game
The Independent Manchester United Supporters Association (IMUSA) believes Roma's Ultras are to travel to the game in Italy on Wednesday to cause trouble.
It follows violence marring United's last two ventures in Europe where fighting broke out at their matches with Lille and AS Roma.
Fans are being warned not to speak English or wear United's colours.
With the first leg of the Milan clash passing off peacefully at Old Trafford last week, it had been hoped the decider at the San Siro would also be trouble free.
However, IMUSA's report, which has been passed onto Manchester United officials, reveals that trains on the Rome-Milan route on Wednesday have all been booked up when usually they would be relatively empty.
As a result IMUSA chairman Mark Longden is urging supporters to be vigilant.
"All I can say is anyone travelling to the game should be aware," he said.
"Everyone knows what happened in Lille and, in particular Rome. If what we have been told is correct, it should just make everyone take a little bit more care."
The report arrived at Old Trafford too late for any specific information to be passed on to the 5,000 United fans who have tickets for the game.
However, the club was lambasted for giving out previous warnings to their supporters concerning a match in Rome earlier this month and possible flashpoints.
Trouble did break out at that match on 4 April, and fans were charged at and beaten by riot police trying to control the violence around the Stadio Olimpico.