Real Madrid defender and captain for the day Sergio Ramos has accepted that he was at fault for Manchester United’s opening goal at the Bernabeu.
Ramos also conceded that the match made for a “bittersweet night” for him and his side.
Danny Welbeck hit the net with a 20 minute header, which will serve as a vital away goal for his team, giving United a minor advantage over Jose Mourinho’s side in the second leg.
Ramos, who served as Real Madrid’s captain for the evening, said of Welbeck: "He got the better of me but it was not a corner in the first place, that is certain. The margin for error in the Champions League is tiny."
Madrid boss Jose Mourinho also suggested an individual error had cost the nine-time champions, telling reporters: "If you see it on television you can see what happened.
"We train, we organise ourselves, we define each player's role, look at the videos to get to know our opponents' strengths at set pieces, but when you lose individual battles there is no level of organisation that can stop it."
Despite the error, Madrid went on to equalise with talismanic Cristiano Ronaldo towering above the United defence to score with his head, ten minutes after Welbeck’s opener.
Mourinho, when asked if the draw was a fair result, said: "It doesn't exist. In football, only the result counts and nothing else.
"We could have scored more goals and they would have been deserved if we had done.
"Despite being a little out of context with the football that they played, they also had clear chances and could have won.
"The expectations and excitement are high for the second leg."