United scored first in Tuesday night's match and looked on course for a place in the quarter finals, before one of their players was sent off in controversial circumstances.
Referee Cuneyt Cakir stunned Old Trafford with what looked to be a harsh red card for Portuguese winger Nani following an aerial challenge on Alvaro Arbeloa.
The decision proved a decisive moment in the game, with the Spanish champions making the most of their advantage by scoring two goals - the second of which came from former United golden boy Cristiano Ronaldo - to snatch victory.
A total of 372,000 viewers in NI watched the drama unfold on UTV.
Michael Wilson, Managing Director, UTV said: "Cristiano Ronaldo scored the decisive goal in his return to Old Trafford last night putting an end to United's European campaign and our audience tuned in in their thousands to see it.
"In fact the audience peaked at 372,000 viewers on UTV last night with an average audience of 288,000 (38%) throughout the whole match which is a tremendous result for football on UTV, well ahead of all other programmes on TV in Northern Ireland at that time."
Meanwhile the debate over the sending off has raged on.
Any time I was sent off in my career I always thought, 'did I give the referee chance to send me off?' And if the answer is yes, then it's out of your hands
Manchester United manager Sir Alex Ferguson was said to be "too distraught" to speak to the press after the game, while Real boss Jose Mourinho admitted "the best team lost".
Roy Keane also weighed in, with the former United captain claiming Nani deserved the red card and describing the winger as "not the bravest player".
He said: "I think the referee has actually made the right call. Everyone's upset about it and it's slightly unlucky, but it's dangerous play. Whether he meant it or not is irrelevant.
"It's dangerous play - it's a red card. You have to be aware of other players on the pitch. Does he think he's going to have 20 yards to himself?
"Whether it's [a brave decision] or not, it's the right decision.
"Whether he meant it or not doesn't matter. Nani's a quick boy to go down anyway. He's not the bravest player on the planet."
However former United defender Gary Neville said the referee had been "poor".
He tweeted: "Been going to OT since age of 5 and I've never seen the whole ground as in disbelief as they were last night at a decision!
"Nani is a player who regularly tries to control a pass like this over his shoulder and its never a red card! Changed the whole game! Poor ref. The crowd actually weren't angry / weren't shouting they were just open mouthed and in shock!
"Anyway it won't be the first time or last! Just ruined a fascinating match and didn't feel right to Utd or Madrid people in the stadium!"