Having already forked out hundreds of pounds to get to Bilbao for a round of 16 UEFA Europa League tie, Manchester United fans are being asked by Athletic Club Bilbao to pay £77.50 for a match ticket.
Rules state both clubs' fans sitting in the same area of the stadium must be charged the same.
Athletic Club is cynically exploiting a loophole by which they give their own members a massive discount, so they will be paying £47 less than United fans.
Despite calls from United and fans' groups, Athletic Club have refused to lower prices.
Sign this petition if you think they should.