In addition to the return of Williams Head Coach Wayne Pivac has made another five changes to the backline that took on defending champions Glasgow Warriors at Parc y Scarlets a fortnight ago.
Liam Williams, Steff Evans and Hadleigh Parkes make up positional changes moving to right wing, left wing and outside centre respectively whilst Aled Davies replaces Gareth Davies at scrum half and Michael Collins comes in at fullback.
Lewis Rawlins is the only change to the pack making his first appearance since Scarlets' defeat to Connacht in late January.
Former Wales Under 20s hooker Ryan Elias joins props Dylan Evans and Peter Edwards on the replacements bench whilst Jack Condy has named hoping to make an appearance for the first time since suffering a shoulder injury at the start of the year.
Speaking earlier this week Wayne Pivac said: "Europe is at stake for us. We'd like to get a result and hopefully put that to bed. We know it's going to be a massive occasion, we're looking forward to it like all the other guys are.
"Their (Dragons) defence has been very, very good in the last three of four games. You can see that there's a real desire and passion in the group and I think they've come very far in a short space of time.
"We've been in the top four up until last week. To be in that top four throughout has been very pleasing. We've eked out the wins when we've needed to. We want to finish the season strongly.
"The way we played in the first half (against Glasgow) and mistakes we made, we've addressed that. We have had a really had a good look at it, put it to bed and moved forward and we're now really looking forward to this game."
Scarlets team to take on Newport Gwent Dragons at Principality Stadium, Saturday 30th April kick-off 5pm;
15 Michael Collins, 14 Liam Williams, 13 Hadleigh Parkes, 12 Scott Williams, 11 Steff Evans, 10 Steven Shingler, 9 Aled Davies, 1 Rob Evans, 2 Ken Owens ©, 3 Samson Lee, 4 Jake Ball, 5 David Bulbring, 6 Lewis Rawlins, 7 James Davies, 8 John Barclay
Replacements: Ryan Elias, Dylan Evans, Peter Edwards, Jack Condy, Morgan Allen, Gareth Davies, Aled Thomas, Gareth Owen
Unavailable for selection: Emyr Phillips (knee), Tom Williams (shoulder), Aaron Shingler (concussion), DTH van der Merwe (shoulder)
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