The Dolphins placed Marshall (hamstring) on injured reserve Monday, Adam Schefter of ESPN reports.
Marshall was already ruled out for Monday's game against the Jets due to a hamstring injury that he suffered during the Dolphins' Week 3 loss to the Bills. He'll now be required to miss at least the next four games, which makes Week 8 against the Falcons on Sunday, Oct. 26 the earliest he is eligible to return. Cornell Armstrong is a candidate to see an uptick in snaps at corner due to Marshall's absence.