For the second consecutive week, Oregon is not sure which quarterback it will face Saturday.

Arizona played its top choice when Khalil Tate returned from a one-game absence due to an ankle injury to throw for 189 yards and three touchdowns in Saturday’s 44-15 win over the Ducks.

UCLA hopes for a similar scenario if freshman Dorian Thompson-Robinson can return from a shoulder injury after missing last week’s 41-10 loss to Utah. In his absence, senior grad transfer Wilton Speight was 20-for-40 for 164 yards. He also ran for 30 yards on eight carries.

“We don’t know who they are going to play, but it comes down to us executing on defense,” Oregon co-defensive coordinator and safeties coach Keith Heyward said.

According to media reports, Thompson-Robinson returned to practice this week, but Speight was running the first-team offense.

Thompson-Robinson would give UCLA more of a dual-threat look, somewhat similar to what Oregon prepared for last week with Tate.

“Dorian will probably keep it more than Speight will, but at the end of the day, we are going to be assignment-driven and everyone has to do their job,” Heyward said. “If Speight is in there, he may not keep the ball, but he has at times to keep you honest and Dorian will keep the ball on the zone read.”

Thompson-Robinson is a true freshman from Bishop Gorman High School in Las Vegas who originally committed to Jim Mora, but was considered a significant signing for Chip Kelly when the new coach was able to keep the four-star prospect.

The 6-foot-1, 205-pounder started the first seven games of the season while completing 60.2 percent of his passes for 1,176 yards and six touchdowns. He has run 45 times for just 70 yards, including 120 yards lost on sacks and negative runs.

Speight has completed 57 percent of his passes for 413 yards and two scores while running for 40 yards in three games.

“They are both very effective,” UO coach Mario Cristobal said. “I think in the conference you will see just about every team has one or the other, a guy that is more of a pocket guy but can still move around and a guy who is a real good athlete.

"From a base defensive standpoint, you have answers for both. Your specialty stuff, third-down stuff, you have to take into account who is in the game. The guys with elite athletic ability can extend the play with their feet so you have to have a plan of them and we certainly do.”