University of Arizona Athletics issued the following annoucement on Dec. 27.
Due to COVID-19 protocols within the USC women's basketball program, Arizona's game at USC, originally scheduled for Dec. 31st, will not be held. The Wildcats and Trojans were set to open Pac-12 play in Los Angeles.
The two programs will work with the Pac-12 to reschedule the game on a mutually agreed upon date.
Original source can be found here.