Scarlets boss Simon Easterby has made five changes to his starting XV for Saturday's Heineken Cup clash with Harlequins at the Stoop.
With club captain Rob McCusker out with a calf injury and Wales international hooker Ken Owens also on the sidelines with an abdominal strain, Easterby has switched Josh Turnbull to number eight alongside Aaron Shingler and John Barclay in the back row while Emyr Phillips will wear the number two jersey.
Amongst the backs, Kristian Phillips replaces Nick Reynolds on the right wing while Scott Williams takes over from Gareth Maule at inside centre.
Easterby believes his players have the ability to cause upsets but will need to bring a big performance from the very outset on Saturday afternoon.
"We've had a very sharp week in training - the boys have worked very hard. There's nothing like Heineken Cup weeks to get everyone motivated and especially an Anglo-Welsh contest and we're confident that if we get our house in order, we can cause other teams problems.
"We've seen it in patches in our first five weeks of the season and we can take a lot from those games. However, we know we'll have to hit a new level this weekend and set our stall out in this opening European fixture. We've only been a few per cent off clicking but there's no room for error in these contests.
"Both sides will be looking to put some frustrating weeks behind them and Harlequins are a very effective team - especially at home."
The Scarlets have only met the Quins once at The Stoop in European competition - losing 29-24 during the 2008-09 season.
Easterby said there was just a sharp focus on the performance they have to bring to Twickenham on Saturday - despite the backdrop of some notable shocks they've brought to the Heineken Cup competition opening rounds in recent years.
These include the big bonus point win away from home against Northampton at Franklin's Gardens in the Heineken Cup in November 2011 and the memorable triumph at London Irish's Madejski Stadium in 2009.
"You can draw on your experiences from those big games - they're pretty special and as players you can take inspiration from those wins, knowing you've done it before; but we have to be very focused on this game, our levels of consistency and our own performance," added Easterby.
"Our scrum has been effective this season; it's something we have put a big focus on for the last 18 months and is certainly adding more to our game with Danny Wilson's input; but it's a constant work on and we have plenty more to do. And when we get some good quality ball delivered to our back line we know how dangerous those players can be; so it should be a great contest on Saturday."
Meanwhile, Harlequins boss conor O'Shea has made three changes to his back-line that played London Irish last weekend.
Tom Williams returns to start on the right wing. Sam Smith switches to the left wing, replacing Ugo Monye who picked up a slight knock last week.
Ben Botica starts alongside Matt Hopper in the midfield and replaces Tom Casson who was also injured last week.
Danny Care starts at scrum-half, with Karl Dickson named on the bench.
George Merrick starts in the second-row, as Nick Easter returns to his more familiar position at number eight.
Among the replacements, Paul Sackey is named.
Harlequins: 15 Mike Brown, 14 Tom Williams, 13 Matt Hopper, 12 Ben Botica, 11 Sam Smith, 10 Nick Evans, 9 Danny Care, 8 Nick Easter, 7 Chris Robshaw (c), 6 Maurie Fa'asavalu, 5 George Robson, 4 George Merrick, 3 Will Collier, 2 Rob Buchanan, 1 Joe Marler.
Replacements: 16 Dave Ward, 17 Darryl Marfo, 18 Kyle Sinckler, 19 Tom Guest, 20 Luke Wallace, 21 Karl Dickson, 22 Paul Sackey, 23 Charlie Walker.
Scarlets: 15 Liam Williams, 14 Kristian Phillips, 13 Jonathan Davies (capt), 12 Scott Williams, 11 Jordan Williams, 10 Rhys Priestland, 9 Rhodri Williams, 8 Josh Turnbull, 7 John Barclay, 6 Aaron Shingler, 5 George Earle, 4 Jake Ball, 3 Samson Lee, 2 Emyr Phillips, 1 Phil John.
Replacements: 16 Kirby Myhill, 17 Rob Evans, 18 Jacobie Adriaanse, 19 Joe Snyman, 20 Craig Price, 21 Gareth Davies, 22 Steven Shingler, 23 Gareth Maule.
Date: Saturday, October 12
Kick-off: 15:40 BST
Venue: Twickenham Stoop
Referee: John Lacey (Ireland)
Assistant referees: Peter Fitzgibbon (Ireland), Olly Hodges (Ireland)
Television match official: Marshall Kilgore (Ireland)