Matthew Stafford left Sunday's game against the Dallas Cowboys with a thumb injury.
He returned for the second half but left following the first possession. He patched it up in the locker room and left the game.
After the 43-20 loss, Sean McVay told ESPN Los Angeles radio he was discouraged.
“It doesn’t seem like it’s good,” he added, but he wants more injury information.
McVay refused to speculate on Stafford's thumb injury's seriousness during his press conference.
“His thumb. The seriousness of such injury will be determined. I won't guess until I hear from the physicians, but he couldn't return, he added.
McVay said Stafford was injured when he dove into the end zone for the two-point conversion after catching a Tutu Atwell throw.