Barcelona signed the ex-Juventus stopper after learning that Marc-Andre ter Stegen would miss the remainder of the season, and he will battle Inaki Pena for the gloves this term, most likely after the October international break.
Head coach Hansi Flick will need to assess the fitness of his squad following Tuesday's 5-0 win over Young Boys in the Champions League, but Inigo Martinez insisted after that clash that he would be fine for the game with Alaves despite being forced off with a muscular complaint.
Eric Garcia is available again after serving a European ban, and it is likely that he will come into the XI on Sunday, with Ferran Torres potentially dropping down to the bench.
Frenkie de Jong made his return from a long-term ankle problem off the bench against Young Boys, but the Netherlands international is not yet ready to start for the club.
As a result, Garcia for Torres could be the only change from the European tie, as Barcelona look to bounce back from their 4-2 defeat to Osasuna in La Liga last weekend.
As well as Ter Stegen, Fermin Lopez, Dani Olmo, Ronald Araujo, Andreas Christensen, Marc Bernal and Gavi remain unavailable for selection due to fitness problems.
Barcelona possible starting lineup: Pena; Kounde, Cubarsi, I Martinez, Balde; Casado, E Garcia, Pedri; Yamal, Lewandowski, Raphinha