Tight end Vernon Davis, the 49ers' second-leading receiver this season, left Sunday's game in the second quarter and was ruled out after being diagnosed with a concussion.
Davis took himself out after dropping a second-quarter pass near the Panthers' 5-yard line and landing hard on his head when tackled by safety Mike Mitchell.
Davis last sustained a concussion Dec. 23 at Seattle, and although he did not return to that game, he did play the following week. He will, of course, have to pass NFL protocol before returning. The 49ers played the second half with only one healthy tight end, Vance McDonald. Third-stringer Garrett Celek was ruled out with a hamstring injury in the first quarter.