The recent arrival from RB Leipzig was not involved in his new club's 2-1 win over Valencia last weekend, having not yet been registered with La Liga.
Barcelona are confident that the Spain star will be available for selection this weekend, but due to a lack of action since the end of Euro 2024, he could be among the substitutes for the first whistle.
Barcelona head coach Hansi Flick may make just the one change to the side that started the season opener against Valencia, with fit-again Pedri likely to come in for Ferran Torres.
Ansu Fati, Ronald Araujo, Frenkie de Jong and Gavi all still unavailable for selection through injury, while Ilkay Gundogan is on the verge of leaving the club to secure a return to Manchester City.
As a result, it is likely that Marc Bernal and Marc Casado will continue in central midfield due to their strong performances in the team's first match of the 2024-25 La Liga campaign.
Andreas Christensen is among the options for change, but it is likely that Inigo Martinez will take to the field against his former club, with Pau Cubarsi also featuring in the middle of the defence.
Robert Lewandowski scored a brace against Valencia last weekend, and the Poland international will again lead the line, while Lamine Yamal and Raphinha should also be in the starting side against Athletic.
Barcelona possible starting lineup: Ter Stegen; Kounde, Cubarsi, I Martinez, Balde; Bernal, Casado; Yamal, Pedri, Raphinha; Lewandowski