The fighters scheduled to compete at Saturday’s UFC Fight Night event in Mexico City officially weigh-in on Friday morning.   The event is headlined by a flyweight rematch between former two-time champion Brandon Moreno (21-7-2) and third ranked Brandon Royval (15-7).  In the co-main event, third-ranked featherweight contender Yair Rodriguez (19-4, 1 NC) faces fourth-ranked Brian Ortega (15-3, 1 NC).   UFC Fight Night: Moreno vs