Newbridge is the venue for the first against second game, kick off 7.15, whilst the Blues have switched their game against the Ospreys from Pontypridd's Sardis Road ground to the Ely Memorial Ground, home of Glamorgan Wanderers (7.15).
Both games have been brought forward from next Wednesday due to a clash with a colleges' competition in England at which many of the regional players will be appearing.
Blues manager Gafyn Cooper said; "You only have to look at the table to see how close competition has been this season. It promise to go right to the wire and we are just glad to be still in there with a chance."
The Dragons, who were celebrating the under 20 crown two weeks ago, are hoping that home advantage will enable them to move closer to the Scarlets and to avenge their 38-18 defeat earlier in the season.
However, the Scarlets will be in no mood to relinquish their advantage at the top and could secure a place in the final if they bag a bonus point win and other results go in their favour.
Dragons: N Williams; A Cooper, J Dabiels, L Robling, A Norton; J Merriman, D Newlands, R Jones, T Rusga, A Yule, R Wilson, T Crandon (capt), G Rogers, G Jones, G Evans
Replacements: A Dix, L Bevan, C Howells, H Lewis, K Tayler, J Evans, M Jolly, L Foley, M Morgan.
Scarlets: L Rees; G North, L Williams, A Warren, J Russell, J Roberts; A Davies,; R Evans, K Myhill, G Havard, G O'Reilly, L Hamilton, E Siggery, L Renalds, S Phillips (capt).
Replacements: R Jenkins, J Howard, R Thomson, S Parry, R Davies, S Shingler, D Ford, J Siddell
Blues: E Jones; A Webber, O Williams, N Gumbleton, I Mortimer; D Bird, T Rowlands; L Smout, I Davies, O Davies, C Hill, M Cook, D Barry, T Young (capt), D Crimmins.
Replacements: C Williams, D Evans, G Roberts, J Barley, J Wilson, S Hopkins, H Thomson
Pld W L D Pts
Scarlets 7 5 1 1 25
Dragons 6 4 2 0 18
Ospreys 6 3 2 1 16
Blues 6 3 3 0 15
G Cymru 7 0 7 0 0