Lucas was hurt trying to bring down running back Felix Jones in Dallas' 38-17 victory. On the tackle, Jones pushed Lucas to the ground, and the ninth-year cornerback landed awkwardly.
Two trainers helped Lucas slowly walk back to the bench. Seahawks coach Jim Mora Jr. did not have an update on Lucas after the game.
Seattle's defense took a hit earlier in the week when three-time Pro Bowl middle linebacker Lofa Tatupu was put on injured reserve after surgery to repair a torn left pectoral muscle. Seattle cornerback Marcus Trufant was active for the first time Sunday, two days after being activated from the physically unable to perform list.
"If we can get through a week without any injuries, that gives us a chance to start building consistency," Mora said.