Former referee Ildefonso Urizar Azpitarte, the refereeing expert for AS, wrote on Monday that Webb taking control of the clash has dented Madrid's chances of a sensational comeback.
"I believe the appointment of the Englishman Howard Webb is unlucky for Madrid," Urizar said. "I do not believe it suits Madrid's style of play. If the game is not tough, with not much physical contact, there are no problems with Webb.
"But if it gets difficult and you must show valour, as we hope happens, he will be an official who stops everything, halts the game too much and gives too many long explanations, cooling down the game. And in the penalty areas, he lets all kinds of things go in order to keep both teams happy."
Real Madrid host Borussia Dortmund for a place in the final on Tuesday night.