The junior quarterback has thrown seven touchdowns and two interceptions in UCLA's two games.
Thompson-Robinson tweeted out Friday night that he does not have COVID-19.
In a tweet Saturday morning he said he's frustrated to not be playing.
I will not have the opportunity to play vs. Oregon today for reasons out of my control. Frustrated I can't help the team but they will still be great regardless! #GoBruins— DTR (@DoriansTweets) November 21, 2020
With Thompson-Robinson out, Chase Griffin is expected to get the start.
Griffin, a freshman, made an appearance in Sunday's win over Cal but did not throw a pass.