The La Blaugrana No.1 missed the weekend win at Sevilla with a muscle injury which forced him off at half-time in the 7-2 thrashing of Racing Santander - and he will also miss Spain's incoming UEFA Nations League games.
Flick had initially looked to be planning for veteran Wojciech Szczesny to fill the gap in Andalucia, but he instead opted for Dominik Livakovic as a late minute pick, with the Croatian thrown in for his debut.
Livakovic was signed in the summer - following Marc-Andre ter Stegen's loan to Ajax - and he conceded the opening goal as Flick faces a major call with Garcia's return date unknown.
"Sometimes you don't just have to analyse everything, you sometimes just have a feeling. That was my feeling, and we made the decision.
"It's not that we don't believe in Szczesny, but I thought Livakovic could be better. It's not a fixed situation; it's a decision for this match."