Observations from warmups before the Arizona Wildcats’ game against Colorado on Friday night at Arizona Stadium (7:45 p.m., FS1):
* Laviska Shenault Jr., the Buffaloes’ star wide receiver, will not play because of a toe injury. Shenault has missed the past two weeks, both Colorado losses. Look for a heavy dose of K.D. Nixon in the passing game in Shenault’s absence.
* Gary Brightwell, Arizona’s No. 2 tailback, is not dressed. Brightwell suffered an apparent ankle injury in the second quarter last week. Anthony Mariscal is listed as the backup to J.