Chiefs LB Drue Tranquill (concussion), S Bryan Cooks (ankle) out

GREEN BAY, Wis. -- The Kansas City Chiefs lost linebacker Drue Tranquill to a concussion in the first half of Sunday night's 27-19 loss to the Green Bay Packers.

Tranquill has started eight of the Chiefs' 12 games as they've played much of the season without the linebacker he replaced, Nick Bolton. Bolton remains on the injured reserve list after having wrist surgery earlier in the season, and he was not in uniform for the Packers game.

Bolton, however, returned to practice last week and could be available for next week's game against the Buffalo Bills.

The Chiefs also lost starting safety Bryan Cook in the second half with an ankle injury. Cook was taken from the field on a cart and was on crutches in the locker room after the game.

Cook, who has started all 12 games, entered Sunday eighth on the team in tackles with 35. He has one interception.

Tranquill is fourth on the Chiefs with 3.5 sacks.