Lock Percival takes the place of club captain Dean Schofield, who drops to the bench, but it is otherwise the same pack which were defeated 13-6 by Perpignan in the Amlin Challenge Cup last time out.
Head coach Richard Hill has opted for a significant rejig of this back-line, though, with Chris Pennell recalled at full-back and Josh Matavesi and David Lemi brought back at inside centre and wing respectively.
Hooker Aleki Lutui will make his 100th appearance in the Aviva Premiership if he comes off the bench.
London Welsh head coach Lyn Jones has made a total of 13 changes following the 27-13 home defeat to Grenoble in the Challenge Cup.
Only full-back Tom Arscott and centre Seb Jewell retain their places as the Exiles bring back the likes of Gordon Ross, Franck Montanella, Sonny Parker and Kirill Kulemin.
Rob Lewis goes straight into the side at scrum-half after being signed on loan from Cardiff Blues until the end of the season.
Worcester Warriors: 15 Chris Pennell, 14 Nikki Walker, 13 Alex Grove, 12 Josh Matavesi, 11 David Lemi, 10 Andy Goode, 9 Paul Hodgson, 8 Semisi Taulava, 7 Matt Kvesic, 6 Neil Best, 5 Chris Jones, 4 James Percival (c), 3 Euan Murray, 2 Ed Shervington, 1 Ceri Jones.
Replacements: 16 Aleki Lutui, 17 George Porter, 18 John Andress, 19 Dean Schofield, 20 Sam Betty, 21,Jonny Arr, 22 Danny Gray, 23 Jon Clarke.
London Welsh: 15 Tom Arscott, 14 Dan Caprice, 13 Sonny Parker, 12 Seb Jewell, 11 Nick Scott, 10 Gordon Ross, 9 Rob Lewis, 8 Ed Jackson, 7 Mike Denbee, 6 Adam Balding, 5 Kirill Kulemin, 4 Jonathan Mills (c), 3 Arthur Joly, 2 Neil Briggs, 1 Frank Montanella.
Replacements: 16 Greg Bateman, 17 Tom Bristow, 18 James Tideswell, 19 Matt Corker, 20 Alfie To'oala, 21 Nick Runciman, 22 Alex Davies, 23. Tom Voyce.
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