Ash missed Texas' 41-7 loss to BYU on Saturday because of concussion symptoms. Swoopes was 20 of 31 passing for 176 yards with one touchdown and one interception in his first career start.
Ash has only appeared in four games since the start of the 2013 season. He was cleared to return this season and played most of Texas' season-opening win over North Texas. Ash later reported headaches and dizziness after the game and hasn't returned. He was on the sideline for the BYU game last week.
Texas (1-1) plays No. 12 UCLA (2-0) this Saturday at Cowboys Stadium in Arlington, Texas.