In total there are 10 internationals named in the starting XV and five on the bench.
Glenn Bryce moves from centre to full-back to make his first competitive start, with captain Peter Murchie partnering Fraser Lyle in midfield.
Scotland internationals Rory Hughes and Lee Jones line up on either wing, while the returning Scott Wight starts at stand-off and Grayson Hart makes his competitive debut for the club at scrum-half, after joining from Edinburgh Rugby in the summer.
In the front-row Jerry Yanuyanutawa starts at loose-head, with Mike Cusack given the nod at tight-head and Pat MacArthur at hooker.
Harley and Cummings combine in the second-row, while Adam Ashe returns from Scotland duty and starts at Number 8. Josh Strauss, who has been named in Scotland's 31-man Rugby World Cup squad, moves to blindside flanker, with Chris Fusaro continuing at openside.
There are five internationals on the bench, with Alex Allan and Tyrone Holmes returning from injury, while Kieran Low, Mike Blair, Rory Clegg and 22-year-old BT Sport Scottish Rugby Academy Stage 3 player Robbie Fergusson could all make their competitive debuts for the club.
Tickets for tomorrow's game are still available from glasgowwarriors.org.
Glasgow Warriors head coach Gregor Townsend said: "We're excited about playing at Scotstoun for the first time this season and we're expecting a capacity crowd to get behind the team.
"Scarlets are a tough side and we know we'll need to be at our best tomorrow night in order to start the season with a positive result.
"Scott (Cummings) has worked really hard during pre-season and has earned his start and Robbie (Fergusson) has also done really well over the last few weeks and could feature at some point.
"We have real depth to our squad and the Rugby World Cup period is an opportunity for our players to show what they can do and we're looking forward to seeing them all represent the club."
Glasgow Warriors team to play the Scarlets, Scotstoun Stadium, Saturday 5 September (kick-off 5.15pm) - live on Sky Sports 4
15. Glenn Bryce
14. Lee Jones
13. Peter Murchie (Captain)
12. Fraser Lyle
11. Rory Hughes
10. Scott Wight
9. Grayson Hart
1. Jerry Yanuyanutawa
2. Pat MacArthur
3. Mike Cusack
4. Rob Harley
5. Scott Cummings
6. Josh Strauss
7. Chris Fusaro
8. Adam Ashe
Replacements
16. Kevin Bryce
17. Alex Allan
18. Zander Fagerson
19. Kieran Low
20. Tyrone Holmes
21. Mike Blair
22. Rory Clegg
23. Robbie Fergusson
Not available due to injury: Alex Dunbar (knee) & Sam Johnson (shoulder).
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