Dani Carvajal has been handed a retrospective one-game ban in the Champions League for a dodgy infringement against APOEL Nicosia in November.
The defender has been a constant figure in Real Madrid's line-up since making a name for himself in the Bundesliga with Bayer Leverkusen.
Since re-joining in 2013, the Spaniard played a crucial role in helping Los Blancos to three Champions League titles in four years, but may have put the dream of three-in-a-row in jeopardy.
With the twelve-time European Cup winners cruising to a 6-0 win in Cyprus, Carvajal took an exceedingly long time to deliver a simple throw-in and was subsequently booked for time-wasting.
After his four previous cautions in the group stage, the referee's decision in Cyprus meant the right-back missed the final match against Borussia Dortmund.
Madrid went on to defeat an out-of-sorts Schwarzgelben, but the result was meaningless since Spurs had already guaranteed top spot beforehand, meaning the Bernabeu side had to settle for second.
While they looked to have gotten away with it, an investigation by the UEFA Control, Ethics and Disciplinary Body found Carvajal to be in breach of rules for deliberately attempting to get a yellow card, and shall miss the first leg of the knockout stages.
Having finished as runners-up, Los Galacticos could be drawn against group winners Liverpool, Paris Saint-Germain and both Manchester Clubs, with the draw taking place on Monday.