But Waunarlwydd will fancy their chances of overturning Glynneath as they can prove stubborn opponents when they put their minds to it.
Another mouth-watering clash is between Glamorgan Wanderers and Llantwit Fardre.
The Wanderers may be struggling mid table in Division 1 East but they were in a no-nonsense mood in the previous round with a convincing 53-3 rout of Builth Wells while Llantwit Fardre had to fight all the way to make the draw after eventually brushing aside Heol y Cyw 17-15.
All fourth round games are to be played on the weekend of February 15, 2014.
SWALEC Plate, Round 4
Glynneath v Waunarlwydd
Caernarfon v Nant Conwy
Nelson v Llangennech
Rhiwbina v Kidwelly
Trebanos / Kenfig Hill v Maesteg Quins
Merthyr v Risca
Glamorgan Wanderers v Llantwit Fardre
Amman Utd v Abergavenny