The one change in the backs from the team that started against London Welsh last weekend, sees Henry Trinder replace Mike Tindall in the midfield as Gloucester continue to field an all English back line.
Up front, Koree Britton will make his first start in the Aviva Premiership at hooker, while Lua Lokotui returns to partner Jim Hamilton in the second row.
Meanwhile, Tom Savage and Akapusi Qera resume their usual positions as blindside and openside flanker respectively.
After three weeks without a game, Davies acknowledged that his team weren't initially at their best against London Welsh last weekend but will be looking for a more complete performance against Harlequins.
"We were probably a bit rusty, definitely didn't work to the patterns that we did earlier in the season, although we saw a bit of it towards the end of the game in the last 20 minutes when we opened it up again.
"What we've done this week is look within ourselves as a group, just refocus on what's important to us and look at the individuals that we have within the team and what we're capable of.
"It's all about how we perform on Friday night. It's a big game, against a tough opponent who have been trailblazing over the last two or three years in terms of their performances and results. So, it'll be a big test for us.
"But we're still very much in the fight. It's about seeing what we can do, and taking our game to the next level."
Rob Cook; Charlie Sharples, Henry Trinder, Billy Twelvetrees, Jonny May; Freddie Burns, Dan Robson; Dan Murphy, Koree Britton, Shaun Knight; Lua Lokotui, Jim Hamilton (capt); Tom Savage, Akapusi Qera, Sione Kalamafoni
Huia Edmonds, Nick Wood, Dario Chistolini, Will James, Andy Hazell, Dave Lewis, Mike Tindall, Martyn Thomas