La Liga's early pacesetters are still having to cope without the services of a number of absentees, including Ronald Araujo, Frenkie de Jong and Andreas Christensen.
Young midfielder Marc Bernal suffered an anterior cruciate ligament injury against Rayo last month and has now been ruled out for 12 months after undergoing surgery.
Long-term absentee Gavi has stepped his recovery from a serious knee injury, but he is still some way off from making a return to competitive action.
Fermin Lopez is also on the absentee list after he sustained a hamstring injury while on international duty with the Spain Under-21s side.
Ansu Fati, who spent last season on loan at Brighton & Hove Albion, is closing in on a return to action after missing the start of the season due to a foot injury, but the forward is unlikely to be risked for Sunday's meeting with Girona.
As long as there are no other injury concerns, Flick could decide to select the same side that started the 7-0 demolition of Real Valladolid before the international break.
Marc-Andre ter Stegen is set to be shielded by a back four of Jules Kounde, Pau Cubarsi, Inigo Martinez and Alejandro Balde.
In midfield, Marc Casado is in line to make a second successive start, and he should be joined in the middle of the park by Pedri.
Raphinha, who netted a hat-trick against Valladolid, will operate from the left flank, while Spain international Lamine Yamal will look to add to the four assists he has already registered this season when he lines up on the left.
Summer signing Dani Olmo will continue to offer an attacking threat from the number 10 position and just behind striker Robert Lewandowski, who has netted four goals in as many games this season.
Barcelona possible starting lineup: Ter Stegen; Kounde, Cubarsi, Martinez, Balde; Casado, Pedri; Yamal, Olmo, Raphinha; Lewandowski