Doug Baldwin came into Sunday's season opener with a knee issue, and he left it with another one.
Baldwin has held out for most of the preseason with a knee injury, but this new sprain is to the opposite knee, Carroll explained. Baldwin said in August that his fickle knee "won't be 100 percent" healthy in 2018.
It is too early to tell how long Baldwin will be out.
Baldwin finished with zero receptions on one target on Sunday. In his stead, Russell Wilson targeted most heavily receivers Tyler Lockett and Brandon Marshall and tight end Will Dissly.
Baldwin led the Seahawks in catches (75) and receiving yards (991) in 2017.