Trains Saturday with the Rugby

Does anyone know what the situation will be on Saturday when catching the train from Grangetown to the valleys via Cardiff Central as normally they only put on a few carriages on but Now with the rugby on Saturday will they have a queing system as they nomally do at Cardiff Central or will our few carriages from Grangetown be affected.
Problem is that if they have a queing system outside Cardiff Central then there will be no room on the valley carriages as our train ater the football normally has no standing room.
I dont trust them to put on extra carriages somehow.

IWhen they say extra trains for the thugby fans they don't mean carriages, they actually mean "engines" to pull the carriages with the fat f*****s in.