That happened when, during the 2nd half, Chilean Villarroel was trying to enter Boca area, and defender Maidana pushed him, but not inside. Vazquez wasn´t well located and the 1st assistant, Walter Rial, was not concentrated at all. Apparently Rial has some kind of problem with his eyes or something like that: all this happened in front of his nose. However, Vazquez conceded Colo Colo a penalty and Rial didn´t say anything. After that the penalty was failed by Fierro.
Before that, the referee overacted when he showed direct reds to Barrios (Colo Colo) and Morel Rodriguez (Boca). That was a little skirmish that should have been solved with two yellows.