No choice for Slovene ref. Pereira had to go

It was the shrug of the shoulders that said it all. What was Slovenian ref Damir Skomina to do with Benfica captain Pereira?
First he mouths an insult clearly comprehensible in many European languages to earn himself a yellow, and then he leaves his studs up in a challenge with Chelsea's Jon Obi Mikel.
Two yellows and the subsequent red are generally a fatal blow in a Champions League game and Benfica's 10-man team  also gave away a stupid penalty with a clumsy challenge on Ashley Cole.
I suspect the 35-year-old Skomina, who has reffed at a top European levels for seven or eight years, would have expected a more sophisticated performance from the Benfica players, but their fouls were obvious.