|Venue: The Den
GREG Halford's early goal consigned Millwall to their 11th home defeat of the season.
Victory kept Nottingham Forest's play-off hopes alive but the Lions still have work to do to prevent a disastrous relegation to League One.
But safety could be secured if Sheffield Wednesday beat Peterborough in Saturday's late kick-off at London Road.
Manager Kenny Jackett made five changes from the midweek defeat to Blackburn Rovers, bringing in Shaun Batt, Nathan Tyson, George Saville, Adam Smith and Sean St Ledger.
Forest took the lead with just eight minutes on the clock when Halford out-jumped St Ledger to head home Andy Reid's corner in front of the travelling fans.
Radoslaw Majewski saw his drive from the edge of the area held by David Forde before Saville crashed a half-volley well over the bar at the other end.
Millwall had appeals for a penalty turned down in the 18th minute when Danny Collins slid in on Batt but the defender looked to have got the ball and play was waved on.
After the Lions had scrambled clear another dangerous Reid corner, James Henry nearly capitalised on goalkeeper Karl Darlow's fumble, but scooped his shot over.
The winger had another effort on goal after Saville's inch-perfect through ball but he drilled into the side netting. Shortly after, Batt flicked a header wide from Alan Dunne's cross.
Batt was brought down on the edge of area seven minutes after half time but Henry curled the resulting free-kick straight at Darlow, who made a comfortable save.
Jackett brought on John Marquis and Andy Keogh from the bench to inject fresh energy into his side but it was Forest who continued to have the better of the chances.
In the 76th minute, Forde made a superb reaction save to deny substitute Marcus Tudgay after he latched onto Lewis McGugan's pinpoint cross.
Millwall looked their most dangerous at set-pieces and Keogh was inches away from turning in Karleigh Osborne's header after Henry's corner from the right.
Henri Lansbury blazed over after a rapid counter-attack before McGugan fired at Forde with striker Simon Cox better-placed to score in the middle.
The Lions threw Osborne up front in a desperate attempt to find the equaliser but it was St Ledger who had their last chance, poking straight at Darlow, who held on.