Fulham’s promotion party was put on hold as Derby came from behind to beat them at Pride Park.
Fabio Carvalho put the runaway Championship leaders ahead but the Rams hit back in the second half, with Luke Plange equalising before an own goal by Tosin Adarabioyo.
Nottingham Forest losing at Luton earlier in the day meant a win would have sealed Fulham’s return to the top flight.
Carvalho gave them the lead by slotting keeper Ryan Allsop after a one-two with Bobby De Cordova-Reid.
But Plange levelled from close range after being set up by Lee Buchannan’s low ball in from the left.
And Derby went ahead when Tosin tried to stop Plange diverting Tom Lawrence’s wayward shot into the net but inadvertently helped the ball in himself.
Fulham can now seal promotion in front of their home fans on Tuesday against Preston.
Fulham: Rodak, Williams (Muniz 81), Tosin, Ream, Bryan, Reed, Cairney (Seri 72), Wilson (Kebano 72), Carvalho, De Cordova-Reid, Mitrovic.