Real Madrid coach Carlo Ancelotti says the dismissal of Giorgio Chiellini changed the complexion of the game following the 2-1 victory over Juventus.
Referee Manuel Grafe chose to issue the Italy international a straight red card on 48 minutes for a seemingly innocuous challenge on Cristiano Ronaldo.
The Portuguese bagged a double either side of a Fernando Llorente equaliser, which proved sufficient in dispatching the Bianconeri, but Ancelotti believes the outcome could have been different had his team not been handed a numerical advantage.
"The game changed," he told reporters. "There are five referees, then they decide to penalise Juventus and we must accept it."
The former Paris Saint-Germain boss went on to claim he was pleased with the result - even if his team failed to put the 10-man Italians to the sword.
He added: "We could have played better, but the win is what's important to us.
"The team is confident and developing well. It's a good result. We won the game after playing well for an hour, then we slowed down.
"I liked that we played well at times and we had balance, though we tired towards the end.
"The intensity has to be different; we had two clear opportunities [at 2-1] and did not take them."
The Blancos, who are yet to drop a point in the competition so far, are in poll position to qualify as Group B winners, with second-placed Galatasaray sitting five points adrift of the Spanish giants on four points.