UCLA could have issues in the secondary when it plays Stanford on Friday at the Rose Bowl.
Defensive backs Ishmael Adams and Priest Willis left Saturday's game against USC with undisclosed injuries. Adams did not play in the second half and Willis was helped off the field in the fourth quarter after a collision with a USC player.
Willis was not at practice Monday. Adams was in uniform, but did not do the pre-practice workout with the defensive backs.
Mora said that Adams was "a lot better than I thought he would be today." Willis was more serious, he said.
"We're not sure what extent it was," Mora said. "All head trauma is significant. This wasn't significant where we are overly concerned."
The loss of Adams would be significant. He plays cornerback, safety and nickel back. He averages 23.3 yards on kickoff returns and 10.4 on punt returns.
Adams has also scored three touchdowns, two on interception returns and one on a kickoff return.
With Adams out, defensive back Marcus Rios would be in line from more playing time.