With tens of thousands of fans of Manchester United and Tottenham expected in Bilbao this week for the Europa League final, UEFA warned them Monday about buying unauthorized tickets which should not get them into the stadium.

Manchester United's Europa League semi-final opponents, Athletic Club, filed a complaint to UEFA against Ruben Amorim's side over treatment of their fans.

Supporters warned about buying tickets from ‘unauthorised third parties’ as thousands prepare to descend on Bilbao