Three goals in the last 10 minutes saw Wycombe's Championship survival hopes suffer a major setback as Luton claimed a 3-1 comeback victory at Adams Park.
But there was still time for Elijah Adebayo to head home his fourth goal of the season to secure all three points for a Hatters side whose mid-table finish appears set.
There were warning sides for Luton as Mehmeti curled a shot over the crossbar early, and Sonny Bradley had to be alert to clear from inside his own area after a Jason McCarthy free-kick.
Ikpeazu outmuscled Pearson on the left and found Admiral Muskwe bursting into the box.
Muskwe was felled by Kal Naismith and up stepped Mehmeti, who dispatched his penalty past Sluga eight minutes before half-time.
And it was not long before Dewsbury-Hall's fierce shot stung the palms of David Stockdale for his first proper save of the match.
The introduction of Dewsbury-Hall meant that there were three Leicester loanees on the pitch at once, alongside Muskwe and Knight, but that swiftly became two after Knight was given a straight red for a lunging tackle on Jordan Clark.
Luton had already made another attacking substitution with LuaLua coming on, and both James Collins and Adebayo blasted over the crossbar.
The breakthrough came 10 minutes from time through Moncur, who had only been on the pitch for three minutes.
Clark was fouled and up stepped the midfielder, whose low free-kick found the bottom corner from 25 yards out.
The momentum had been with Luton since the Knight sending off and the goal saw them push on.
Five minutes later, LuaLua was picked out from a short corner and off-balance he unleashed a curling shot into the corner of the net.
So far it had been the substitute show but Adebayo put the gloss on the win two minutes from time after his towering header from a Cornick cross found the back of the net.
The result leaves Wycombe nine points from safety with just five games remaining.