Just about the only positive for Leicester was Harry Winks’ return as he replaced the injured Hamza Choudhury to make his first appearance since 29 November after being frozen out by Cifuentes.
Conor Coady impressed on his Charlton debut as a holding midfielder against his former side following his loan move from Wrexham, and Latics boss Nathan Jones will be delighted with his side’s response after he accused them of treating last weekend’s derby drubbing by Millwall “as a day in the sun”.
The game’s decisive moment came when Okoli was rightly shown a straight red card for pulling back Leaburn when the Foxes defender was the last man.
And after Harry Clarke had a header controversially disallowed for a foul by Leaburn, Charlton’s top scorer Carey gave them the lead in the 36th minute with his seventh goal of the season.
Clarke swung in a cross from the right and Carey lifted the ball over Ricardo Pereira with his first touch before volleying home left-footed with his second.
Leicester were a mess, and in the fourth minute of first-half stoppage time, Dykes steered home Luke Chambers’ cross right-footed to register his first Addicks goal since joining from Birmingham just over two weeks ago.
Leicester rallied in the second half, but spurned a glorious chance to haul themselves back into the game on 56 minutes when Ayew hit the post from a penalty after Abdul Fatawu was pulled back by Amari’i Bell.
Thomas Kaminski saved a 20-yard drive from Pereira, and many unhappy Leicester fans left the King Power Stadium before full-time.