Ethier left the field with a recurrence of stiffness in the middle of his back, which he originally experienced on the day of the first full-squad workout and which manager Don Mattingly said developed from moving boxes before Spring Training started.
Ethier had already been scheduled to skip Sunday's game, but he played catch and took batting practice beforehand, and he is scheduled to start Monday's game against the Angels in Tempe, Ariz.
"It doesn't sound like he's restricted in any way," said Mattingly. "[Trainer Sue Falcone] has worked on him for this before. She doesn't seem too concerned. I'm probably a little more than she is. We'll be cautious. There's no need to rush him."
Sellers, who developed headaches after being hit in the chin by a bouncing batted ball on Saturday, sported a small bruise but said that the headaches are gone, and he was in the starting lineup for Sunday's game with the Cubs.