Njoku, who missed last week's game against the Baltimore Ravens, rejoined the team in time to practice Thursday. Cleveland, however, has 11 starters on the COVID-19/reserve list, including quarterback Baker Mayfield and starting safety Ronnie Harrison who was added Thursday.
With Mayfield likely to miss Saturday's game, the Browns also elevated quarterback Nick Mullens to the active roster Thursday. Case Keenum will get the start at quarterback if Mayfield is ruled out. Mayfield will need to turn in two negative tests 24 hours apart to play Saturday.
Coach Kevin Stefanski was away from Thursday's practice, as well, after testing positive for COVID-19. If Stefanski does not produce two negative tests in time, special teams coordinator Mike Priefer will serve as Cleveland's acting head coach.