Head coach Jim Harbaugh told reporters Monday that Njoku (fibula) and Charlie Kolar (forearm) will both go on injured reserve, Kris Rhim of ESPN.com reports.
Both Njoku and Kolar sustained their injuries during Sunday's 26-14 loss to the Raiders, with the former being carter off the field during the second quarter. Both tight ends will be required to miss at least the next four games, so the earliest Njoku can return is Week 8 against the Rams on Sunday, Nov. 1. For the time being, second-year pro Oronde Gadsden, who posted a 49-664-3 receiving line on 69 targets across 15 regular-season games last year, is the only healthy tight end on the Chargers' active roster.