Around 45,000 supporters inside the Santiago Bernabeu opted for an unusual way to show their backing for the Portugal star as he looks to triumph over the likes of Lionel Messi
Approximately 45,000 supporters in the Spanish capital donned the disguise, with the man himself unable to take to the pitch due to a thigh injury.
The masks reportedly carry instructions for the wearers to put them on in both the seventh and 77th minute of Wednesday's clash, as part of an additional show of solidarity for the Portugal captain.
Ronaldo, who scored a remarkable 25 goals in 18 games this season prior to his injury sustained in the win over Almeria, is one of the frontrunners for this year's Ballon d'Or, along with current holder Lionel Messi and Bayern Munich star Franck Ribery.
Madrid need just a point from their remaining two games against Galatasaray and Copenhagen to secure their place in the next round of the Champions League.