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.
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.