With just under 10 minutes of normal time remaining, the south Londoners were celebrating a fifth. Ola-Adebomi and Mustapha combined once more in a great move, with Mustapha being denied a hat-trick following a good save, but Ola-Adebomi was on hand to tuck in the rebound.
In the five minutes of stoppage time that were added on substitute Drakes-Thomas almost got a debut goal to remember, but his curling effort was palmed away by Curd.
There was a sixth goal to be had, completing the rout in stoppage time. Zach Marsh netted his fifth of the season, following great work from Drakes-Thomas in the middle to pick him out.
Palace were celebrating their biggest win of the campaign and redemption for the 4-2 defeat a few weeks earlier. The incredible victory sees Powell and his men march on into the semi-final where they will take on either Fulham or Southampton.
**Palace:** Moulden (GK), Kporha (Grante, 87), King, Jemide, Browne, Gibbard (Marsh, 84), Cardines, Rodney, Ola-Adebomi (Drakes-Thomas, 84), Mustapha (Williams, 84), Umeh (Reid, 71).
**Chelsea:** Curd (GK), Hughes (Kavuma-McQueen, 63), Murray-Campbell, Emenald, Samuels-Smith (Olise, 90+3), McMahon, Antwi (Ampah, 58), Rak-Sakyi, McNeilly, Dyer, Stutter (Mheuka, HT).
Sub not used: Merrick (GK).