Ronaldo was given his marching orders for an off-the-ball incident with Murillo.
Felix Brych showed the veteran a red card for an incident involving Jeison Murillo, although the Italian coach didn't want to focus on the perceived injustice the Bianconeri felt.
The Portugal captain looked baffled and kept protesting his innocence, briefly laying on the ground to express his disbelief.
Juventus hosts Young Boys next in the competition before two straight games against United, with the first match in England on October 23. Known for being pretty theatrical with his on-field antics, Ronaldo has, on more than one occasion, exaggerated a fall to the turf to have a decision go his way.
A first red card in La Liga came in Ronaldo's debut season for two petulant late bookings coming after he had missed a penalty and also scored Los Blancos' fourth goal in a 4-2 win.
There was a third penalty in the match deep into stoppage time but Daniel Parejo saw his effort saved by Wojciech Szczesny as Valencia were denied a consolation goal.
Jose Mourinho's men were inspired by Paul Pogba on the artificial pitch, as the French World Cup victor drilled home a brilliant opener before converting a penalty on the stroke of half-time.
Manchester City suffered a surprise 2-1 defeat at home to Lyon in Group F.
Meanwhile, despite playing one down for about 60 minutes of the game, Juventus never stopped attacking as the manager substituted Pjanic for Douglas Costa.