Said Benrahma grabbed a hat-trick to move the Bees to within two points of second-placed West Brom. The Baggies are in action against Hull on Sunday.
Benrahma opened the scoring after 19 minutes then made it 2-0 just before the hour-mark with what looked like an intended cross.
The Algerian completed his hat-trick before the afternoon went from bad to worse for the visitors, who had entered administration this week, as Joe Garner was sent off for a bad challenge.
Leeds meanwhile took a huge stride towards the Premier League as goals from Patrick Bamford, Kalvin Phillips and Mateusz Klich saw them to a 3-1 win at Blackburn.
Bamford pounced on an error in the Rovers defence to put his side in front after just seven minutes and Phillips doubled Leeds' advantage with a 40th-minute free-kick.
Adam Armstrong dragged Rovers back into the game in the 48th minute but Klich made sure five minutes later when he struck a deflected effort from the edge of the box.
Fulham also kept their promotion bid alive as Josh Onomah lashed the only goal of the game deep into stoppage time to sink Birmingham 1-0 at Craven Cottage.
Additional reporting from Press Association