Aitor Karanka has warned his Middlesbrough players against the dangers of a giant-killing act versus Accrington Stanley having been on the receiving end of one of the biggest shocks in the history of the Copa del Rey.
The former Real Madrid defender remembers all too well the night in December, 2000 when the Spanish giants were beaten by third-tier CD Toledo.
The Real team that night included the likes of Fernando Hierro and Fernando Morientes but they found themselves two goals down inside 14 minutes and were beaten 2-1.
And Karanka said: 'When I was with Madrid we had won the Champions League and the following season a team in Segunda B beat us in the cup.