UFC 180 : VELASQUEZ vs. WERDUM is the fastest sell - out in the history of the Arena Ciudad de Mexico .
UFC will also set a new attendance record with over 20,000 fans attending the monumental event .
UFC 180 : VELASQUEZ vs. WERDUM is the fastest sell - out in the history of the Arena Ciudad de Mexico and it will also set a new attendance record with over 20,000 fans attending the monumental event .