Millwall secured their Championship safety as Duncan Watmore scored the winner against his former side Sunderland.
After a goalless first half, Watmore came off the bench to fire home and give the Lions their third win in a row.
Sunderland threatened but were unable to find the breakthrough and will finish in mid-table.
The Black Cats, who are under interim boss Mike Dodds, have not won at the Stadium of Light since beating Plymouth on 10 February.
Ex-Lion Dan Ballard came close to opening the scoring for the hosts, heading over the bar from close range early on.