Kohlmann is out, he wants to come back in Munich. Maybe Kas has a small chance, because he and Petzschner beat teams like Knowles/Nestor and Erlich/Ram indoors.
Yes, would be a great option, too, because such a well-working doubles team means something. Only risk is that Kas doesn't have the Davis Cup experience.
But against Spain, Kühnen needs a true and only doubles team that the singles players can rest on Saturday.