Kirk (calf) was placed on injured reserve by the 49ers on Sunday with a designation to return.
Kirk missed the entirety of the preseason after suffering a calf injury at practice July 26, and he will now be forced to sit out at least four contests to open the regular season. The wide receiver signed with San Francisco in the offseason, and he was expected to occupy a prominent role on offense. In his absence, rookie wideout De'Zhaun Stribling (shoulder) will have a chance to be an impact player in his NFL debut Week 1 against the Rams in Australia.