It was an incredible shame for Manchester United that their Champions League hopes were left in complete tatters by the inexplicable decision by the referee to send Nani off for an innocuous challenge on Real Madrid full-back Arbeloa.
At the very worst, it was a yellow card. There was absolutely no malice in the challenge whatsoever, his eyes were on the ball the whole time it was in the air and he was extremely unlucky to catch Arbeloa as he came from behind him.
For United to hang onto their lead against one of the greatest teams in the world for over half an hour was always going to be asking a lot.
However, it would be unfair on Real Madrid to completely blame the referee. The sending-off changed the number of players on the pitch, but it was Jose Mourinho who took advantage of his good fortune and changed the course of the match.
As soon as United were reduced to 10 men, Luka Modric was on the touchline ready to enter the fray.
Mourinho recognised that Madrid were now set to dominate possession and he needed someone with the probing skills of Modric in order to make the breakthrough.
The Croatian has endured an indifferent first season in Spain following his big-money move from Tottenham Hotspur last summer. In and out of the team, he has yet to really establish himself in Jose Mourinho's side.
How that soon changed.
Did Nani deserve to be sent off?
He came on and immediately looked dangerous, always looking for the killer pass that could open up the resolute Manchester United defence.
When he picked up the ball and assessed his options 30 yards from goal, there seemed very little on for the talented midfielder. That changed in an instant. Two touches, then he smashed an unstoppable shot past the desperate dive of the impressive David de Gea.
From there, it was always going to be Real Madrid's time to go and win the game.
As against Barcelona in their last two games, they did so ruthlessly. A quick break down the right flank left the dangerous Higuain with acres of space to pick out a man, which he did.
It had to be that man at the back post. Ronaldo scored to put the tie beyond United, but his celebration was muted in respect for the fans who still adore him.
This match once again proved why many people regard Mourinho to be the best manager in the game. He reacted quickly to the game situation and his side emerged victorious. United will feel hard done by the officiating, but Madrid were arguably the better team.
Mourinho and Real Madrid remain on course for their 10th European Cup.