Any manager will tell you that substitutions don't always go to plan, just ask Newcastle boss Rafa Benitez, who saw utility man Isaac Hayden sent off just 21 minutes after coming on in Saturday's Premier League clash with Cardiff.
A combination of starter Javier Manquillo having a torrid first half and suffering a blow to the ankle just before the half-time whistle saw Hayden replace the Spaniard at right-back for the second half, but things didn't exactly go to plan.
The former Arsenal man looked clumsy and lethargic against the fleet-footedness of Josh Murphy, who had previously tormented Manquillo.
Murphy was Cardiff's biggest threat throughout, so it was only fitting that he drew the red card.
As he looked to receive a routine pass on the turn just inside the Newcastle half he was scythed down by Hayden, who caught him high on the ankle and calf.
The referee gave himself a moment to think before reaching for his pocket and producing the red card.