The Saints Reserves play host club Brecon Corries on Wednesday and need a win or a draw to reach the final, Treharris won the other group edging out Gwernyfed into second place.
Rob Snedden and Ceri Ward have pulled out last minute and will be replaced by Courtney Metcalfe and Brian Goodwin.
The Saints beat Sennybridge 3-2 in their first match, Senny then pulled off a shock win by beating The Corries 1-0 which means all 3 sides could qualify depending on the result.
Squad- C.Lloyd, S.Bradley, A.Winstone(c), L.Pugh, Z.Snape, G.Jenkins, J.Howard, T.Weaver, K.Goodwin, R.Snedden, W.Goodwin, C.Ward, H.Williams, T.Wilkes.
Brecon Corries v Saints Reserves. KO 6.45pm.