In the forwards, Huia Edmonds comes in for Darren Dawidiuk who picked up a knee injury against Wasps while England international number eight Ben Morgan is ruled out with a dead calf.
Finally, Peter Buxton, who has been in fine form in the Aviva Premiership A League, is named at blindside flanker with Sione Kalamafoni moving across to number eight.
It will be Gloucester Rugby's first meeting with London Welsh in the Premiership at the unfamiliar surroundings of the Kassam Stadium.
Lyn Jones' side have won their last two games having experienced a difficult first two games in the top flight and Davies admitted this week that this recent upsurge in form simply reiterates how tough this weekend's game will be.
"It's very important that we've got the right mindset going into Sunday to play London Welsh.
"It's going to be a physical encounter. I think that the two sides that they've beaten probably didn't give them enough respect and, because of that, they finished on the wrong end of the result.
"They're a very strong team, a proud side. They've got a lot of points to prove, individually and collectively, and, if you get it wrong against them, they will beat you."
Rob Cook; Jonny May, Mike Tindall, Billy Twelvetrees, James Simpson-Daniel; Freddie Burns, Dan Robson; Nick Wood, Huia Edmonds, Rupert Harden; Tom Savage, Jim Hamilton (capt); Peter Buxton, Andy Hazell, Sione Kalamafoni
Koree Britton, Dan Murphy, Shaun Knight, Will James, Akapusi Qera, Dave Lewis, Henry Trinder, Martyn Thomas