The team provided no further details on the seriousness of the injury. Smith, who leads the Panthers in receptions (45), receiving yards (590) and touchdowns (six), also sat out practice on Wednesday.
Starting safety Deke Cooper also returned to practice after sitting out Wednesday's workout with a shoulder injury. Running back DeShaun Foster was back on the field after missing a day with a sore toe.
Defensive tackle Damione Lewis (shoulder) missed his second straight practice.
Copyright 2007 by The Associated Press