Under UEFA's disciplinary code, red-card suspensions do not expire at the end of a season the way yellow cards do, and they follow a player even if he switches clubs in the meantime.
That is the situation Real Madrid now find themselves in ahead of their Champions League opener against Inter Milan at the Santiago Bernabéu on 8 September, with head coach José Mourinho unable to call upon three key midfielders.
Arda Güler and Eduardo Camavinga were both sent off for second yellow cards in last season's quarter-final second leg against Bayern Munich, a tie Real Madrid lost on the night. Güler's dismissal came after the final whistle, for remonstrating with the referee, while Camavinga picked up his second caution in the closing stages.
Bernardo Silva's suspension dates back further and was carried over from a different club altogether: he was sent off for a deliberate handball that denied Real Madrid a goal during last season's round-of-16 second leg, while he was still on Manchester City's books. Vinícius Júnior converted the resulting penalty, and Bernardo Silva now carries the ban with him to the Bernabéu having since signed for the club he was originally punished for playing against.
None of the three offences were wiped by the change of season, since UEFA's regulations state a red card carries at minimum a one-match ban into the player's next European club fixture, regardless of any accumulated yellow cards being cleared.
The suspension also applies automatically, without any need for further notice from UEFA. A similar case saw Alex Oxlade-Chamberlain forced to serve out a suspension for Celtic that he had picked up almost three years earlier while at Besiktas.
The timing is awkward for Mourinho, given how central all three have become to his early-season plans.
Güler and Bernardo Silva in particular have emerged as key figures in his midfield structure, with the Portuguese used as one of the primary organisers alongside a deep-lying pivot and the Turkish international operating just ahead of him between the lines. Camavinga, still working his way back to his best form, has also been a regular feature of the head coach's plans.
With Aurélien Tchouaméni not yet fully available and Federico Valverde the only senior option left standing, Mourinho will have to reshape his midfield from scratch for a daunting opening test against the reigning Italian champions — the first serious selection puzzle of his second spell in charge.