The Wales star damaged a groin during the Scarlets 49-16 Pool Five hammering at Clermont Auvergne last weekend – Gareth Maule takes his place.
Andy Fenby returns at left-wing after recovering from a dead leg with Morgan Stoddart, who was sent off after being yellow-carded twice, demoted to the substitutes bench.
Scarlets Head Coach Simon Easterby makes no changes up front. New second row signing Argentinean international Tomás Vallejos comes onto the bench while fellow second row Sione Timani is ruled out with a minor knee injury.
Easterby said the Scarlets were eager for their second European contest against Heineken holders Leinster after the disappointment in France, and they look forward to the challenge and intensity of playing Heineken rugby on home soil this weekend.
“We can’t read too much into our first result, we know that Leinster will come here with a renewed intensity and ambition not least because it’s Heineken Cup second round but they are the holders of the European Cup and showed last week against Exeter that they won’t give up that crown without a fight,” he said.
“Our games against Leinster are always highly competitive and tightly fought contests and we know that after our fortunes in France last week, we need to get a result here to maintain a grip on our European campaign.
“The boys have had an excellent attitude this week. After the bitter frustration last weekend in France and a lot of tired and bruised bodies – the work ethic in training, coupled with the effort and commitment they’ve shown from Monday morning to pick themselves up and re-focus on this huge game has been significant.
“With four players making their Heineken Cup debuts last weekend, Samson Lee, George Earle, Joe Snyman and Richard Kelly there was no lack of edge, spirit, courage or determination from the boys and we can take confidence from our opening 40 minutes.”
“This is a must win game for us but one that is still firmly in our grasp. I have no doubt it will be another great Scarlets European occasion and we’ll be delighted to welcome crowds of supporters from across our region.”
Scarlets: 15 Liam Williams, 14 George North, 13 Gareth Maule, 12 Scott Williams, 11 Andy Fenby, 10 Rhys Priestland, 9 Tavis Knoyle, 1 Phil John, 2 Matthew Rees, 3 Samson Lee, 4 George Earle, 5 Johan Snyman, 6 Aaron Shingler, 7 Josh Turnbull, 8 Rob McCusker (capt).
Replacements: 16 Ken Owens, 17 Shaun Hopkins, 18 Deacon Manu, 19 Tomás Vallejos, 20 Johnathan Edwards, 21 Gareth Davies, 22 Aled Thomas, 23 Morgan Stoddart.
