Many also focused on comments from Real manager Jose Mourinho that the "best team lost", with The Times saying his humble reaction was essentially an "audition" to succeed Alex Ferguson as United manager.
In a match which raised many questions, the papers also speculated that the decision to leave Wayne Rooney on the bench at the start of the match left a huge question mark over his future at Old Trafford.
The Daily Telegraph headlined its coverage "Cheated", focusing on Turkish referee Cuneyt Cakir's decision to send off Nani when most observers had expected a yellow card at worst.
"This was a good game ruined by a bad referee," wrote the Telegraph, saying it was a "terrible decision".
The Times said the sending-off had seemed "extremely harsh" because it came after United had taken a 1-0 lead and a 2-1 lead overall in the tie.
"For a time, this had seemed to be shaping into one of Ferguson's great triumphs, but it ended up as an addition to a litany of Champions League hard-luck stories -- Borussia Dortmund in 1997, Bayer Leverkusen in 2002, Porto in 2004 and Bayern Munich in 2010 -- and this one seemed to bring a genuine cause for grievance."
Under a photograph of Ferguson jabbing an angry finger in the referee's direction, The Sun's headline was "Broken - Fergie distraught after Nani red card KO's Utd".
All the papers highlighted that Ferguson had been too incensed by the decision to speak to reporters afterwards.
Mourinho's performance in his press conference, when he refused to question Ferguson's team selection and insisted that his side were inferior despite the result, "was more saccharin than a Hollywood teen movie", according to The Times.
The Times also speculated that his low-key gesture of consoling Ferguson before walking off the pitch with two minutes of the match remaining was designed to appeal to United directors.
For Rooney meanwhile, who only entered United's biggest match of the season in the 73rd minute, The Times said the writing could be on the wall -- and super-rich Paris Saint-Germain were said to be watching the situation closely.
"Wayne Rooney once had the gall to ask in public whether Manchester United were good enough for him. Last night the question was fired back at the demoted striker: are you good enough any more for United?"