"Veteran referee Pierluigi Collina, regarded as one of the world's finest referees during his refereeing career, earning the title of FIFA's 'Best Referee of the Year' in six consecutive years, awarded Turkish official Cuneyt Cakir an outstanding score for his performance during Manchester United's match with Real Madrid on Tuesday. Although many supporters felt Cakir's decision to send off United winger Nani was extremely harsh, Collina, UEFA's head of referees, gave him an overall rating of 8.2."
http://www.ibtimes.co.uk/pierluigi-collina-c-neyt-akir-443482
"Cakir sent off Nani for serious foul play, which means a player is dismissed for using "excessive force or brutality against an opponent when challenging for the ball when it is in play". The laws further state: "A tackle that endangers the safety of an opponent must be sanctioned as serious foul play." Following these laws to the letter, it is easy for everyone to understand why Cakir was not wrong to send off Nani. Cakir's view is Nani endangered the safety of his opponent."
"While one cannot accuse Nani of having deliberately committed this foul, one may well accuse him of risking the mere opportunity that his stretched studs could seriously hurt an opponent. Severely endangering one's opponent, specially with stud-up and foot-up tackles, must be red-carded - the Laws of the Game (Law 12) clearly define that: "A tackle that endangers the safety of an opponent must be sanctioned as serious foul play." So, even though the sending-off might have aroused a harsh impression among supporters, spectators and players, Çakır was right in the end."
http://footballrefereeing.blogspot.com/2013/03/nanis-red-card-as-paramount-example-to.html