The Chargers activated Niemann (hamstring) off injured reserve Saturday.
Niemann has yet to play a game this season, as he landed on IR in late August due to a hamstring issue. He was designated to return Oct. 2 and logged a trio of full practices this week to set himself up for activation. Niemann still carries a designation of questionable into Sunday's contest versus Denver, and if he plays it likely be in a rotational role.