Demarcus Dobbs left Sunday's game against the Miami Dolphins in the first quarter with a right knee injury and will not return. The San Francisco 49ers' tight end and defensive end didn't look too hurt coming off of the field, but the injury is apparently somewhat serious because he was ruled out for the rest of the game rather quickly.

Dobbs is the 49ers' third tight end and second backup defensive end behind Ricky Jean Francois, making him a rare two-way player, but he appeared to have made the switch to just tight end this week. He was listed as only an offensive player for the Dolphins game, marking the first time all season he wasn't designated as a two-way player.

It is unlikely that San Francisco will be hurt too badly by Dobbs' absence today, but if he is out an extended period of time their depth will be tested by the unavoidable late December injury pileup.