Matt Corker comes in for Russian international Kirill Kulemin in the second row for what will be appearance number 155 for the Exiles, and reforms his partnership with captain Jonathan Mills from the Championship final.
There’s wholesale changes in the back row with Mike Denbee named at openside in place of Lee Beach and Ed Jackson selected at number eight – the position from which he contributed 11 tries to Welsh’s Championship winning season.
Daniel Browne moves from number eight to blindside flanker in place of Ed Williamson.
The only change in the backs is at scrum half, where Welsh give a first start to Tyson Keats, who joins the Exiles from Italian side Aironi Rugby.
Friday’s meeting will be the first between the two clubs since Harlequins’ 2005/06 National League One promotion winning season. Harlequins winning both games, which were both played at the Stoop, 43-23 and 28-17.
London Welsh: 15. Tom Arscott, 14. Phil Mackenzie*, 13. Sonny Parker*, 12. Hudson Tonga’uiha*, 11. Joe Ajuwa, 10. Gordon Ross*, 9. Tyson Keats, 1. Frank Montanella*, 2. Neil Briggs, 3. Paulica Ion*, 4 Jonathan Mills ©, 5. Matt Corker, 6. Daniel Browne, 7. Mike Denbee, 8. Ed Jackson.
Replacements: 16. Dan George, 17. Tom Bristow, 18. Arthur Joly, 19. Kirill Kulemin*, 20. Alfie To’oala*, 21. Nick Runciman, 22. Seb Jewell, 23. Nick Scott.