Wales prop Rhys Thomas has been named to start in the XV announced for the first half along with flanker Richie Pugh, Scots international wing Sean Lamont and centre Gareth Maule. New signing Jamie Corsi starts on the bench.
The first half will also be the first chance for supporters to welcome home new Wales caps Jonathan Davies at inside centre and Daniel Evans at full-back.
Former skipper and new player/coach Easterby starts at 6 behind a youthful second row of Lou Reed and Dominic Day.
The Scarlets second half team features new recruits such as second row Damien Welch and No 8 Ben Morgan. Behind the scrum there will be a Parc y Scarlets debut for wing Andy Fenby and big chances for young talent such as Dale Ford at full-back and Scott Williams at inside centre.
Wales caps Vernon Cooper and Dafydd Jones are among the experienced personnel after the break along with prop Deacon Manu and centre Rob Higgitt.
Scarlets head coach Nigel Davies said of his squad at the region: "I'm really pleased with the energy they've shown in pre-season. They're young and will evolve as a group this year, building on the progress they made last season.
"I'm excited about them - I believe in them completely and I think the performances at the end of last season showed that the investment that had gone into this young group was starting to pay off.
"They've got to take it onto the next level now and I believe that the substantial amount of experience we have in the squad will be very important to this."
Scarlets v Bath, Simon Easterby Testimonial, Saturday, August 22, 4pm
First Half - 1 Phil John, 2 Ken Owens, 3 Rhys Thomas, 4 Lou Reed, 5 Dominic Day, 6 Simon Easterby, 7 Richie Pugh, 8 David Lyons (c), 9 Martin Roberts, 10 Daniel Newton, 11 Sean Lamont, 12 Jonathan Davies, 13 Gareth Maule, 14 Lee Williams, 15 Daniel Evans. Reps - 16 Jamie Corsi, 17 Aaron Shingler, 18 Rob McCusker, 19 Josh Turnbull.
Second Half - 1 Deacon Manu, 2 Emyr Phillips, 3 Matthew Evans, 4 Vernon Cooper, 5 Damien Welch, 6 Dafydd Jones, 7 Jonathan Edwards, 8 Ben Morgan, 9 Gareth Davies, 10 Cerith Rees, 11 Andy Fenby, 12 Scott Williams, 13 Rob Higgitt (c), 14 Darren Daniel, 15 Dale Ford. Reps - 16 Jamie Corsi, 17 Aaron Shingler, 18 Rob McCusker, 19 Josh Turnbull.
Photo Nigel Davies meets the media this week