Blues welcome the French Top14 side to the Welsh capital for the first-ever clash between the two teams. And Director of Rugby Mark Hammett has named a powerful team as he makes six changes to his line-up.
Fly half Davies, the late hero of the epic home European victory over Toulon last season, and scrum half Williams are both selected among the backs.
Positional changes see Rhys Patchell move to full back while Adam Thomas switches to outside centre and is paired with Gavin Evans in midfield.
Richard Smith is named on the wing with Alex Cuthbert missing the game with a minor strain. The Welsh wing is not risked in this fixture and is expected to return for next week’s away clash in Italy.
Prop Sam Hobbs also makes a return to the starting selection, alongside skipper Matthew Rees and Adam Jones.
Two changes in the back row result in Macauley Cook coming in at blindside flanker while Italian international Manoa Vosawai plays at Number Eight.
Hammett said: “It’s fantastic to be back home, after three successive away games, and all the players are looking forward to the challenge. As a region we have a proud past in Europe and we must look to build on that history and launch our latest campaign with a victory.
“Grenoble have enjoyed a strong start to the Top14 season and go into every game with real intensity. We must ensure our physicality and game plan is spot on. But while we are more than aware of the threat they pose, it’s imperative our focus is on ourselves and moving forward as a unit.
“The competition for ever jersey is fierce with many positions tightly contested. We make a number of changes to the starting line-up and are looking forward to seeing those players really stake a claim for even more rugby.”
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Cardiff Blues: 15 Rhys Patchell, 14 Richard Smith, 13 Adam Thomas, 12 Gavin Evans, 11 Geraint Walsh, 10 Gareth Davies, 9 Lloyd Williams; 1 Sam Hobbs, 2 Matthew Rees (c), 3 Adam Jones, 4 Jarrad Hoeata, 5 Filo Paulo, 6 Macauley Cook, 7 Sam Warburton, 8 Manoa Vosawai
Replacements: 16 Kristian Dacey, 17 Gethin Jenkins, 18 Scott Andrews, 19 Josh Turnbull, 20 Josh Navidi, 21 Tavis Knoyle, 22Cory Allen, 23 Dan Fish