Ex-referee Graham Poll writes in the Daily Mail...
Referee Atkinson got the big calls wrong.
Referees are remembered for their big decisions in big games. Unfortunately Martin Atkinson got some wrong on Tuesday night and they cost Manchester United. Atkinson failed to deliver consistency in similar incidents, the basic requirement for match officials. In the first half, Manchester United were denied a penalty when John Terry handled a shot from distance. Although his hands were by his side, the ball travelled a long way and Terry ensured that the ball did not pass - a clear offence. Nothing was given. However, when Yury Zhirkov took the opportunity to go over Chris Smalling's outstretched leg, Atkinson had no hesitation in awarding the home team a spot kick. It was soft, but just about the correct call. An even clearer example came when David Luiz deliberately tripped Wayne Rooney off the ball - a clear cautionable offence. As he had already been cautioned, Luiz should have been dismissed. Nemanja Vidic was not afforded such tolerance later in the game.
source : manutd.com
My words - as mentioned before guyzz, we're not judge or critics only when we are lose, but the facts is everybody (esp pro person) also have the same eyes like us...red devils fans. hihi. peace!!