San Francisco 49ers cornerback Chris Culliver went down with an injury at the end of the first quarter of Sunday's game against the Dallas Cowboys. He eventually got on his feet, but looked a little woozy.

Rookie cornerback Dontae Johnson replaced him on the field.

The 49ers had already lost starter Tramaine Brock earlier in the game.

Update:

Matt Maiocco of CSN Bay Area is reporting that Culliver is being evaluated for a head and neck injury and that his return is questionable.

Update 2:

Maiocco reports that Culliver has a concussion and has been ruled out of this game.