Based on what we have seen, FDJ MUST play against Bayern. Since Busi is a lock at CDM, should be on the left. Should go with 4-4-2 diamond there imo.
-------------MATS-------------
Semedo--Pique-Lenglet--Alba
-----------Busquets-----------
----Vidal----------De Jong----
-------------Puig---------------
------Messi---------Fati--------
IMO, with that lineup, you lose the deadweights in attack (Griezmann, Suarez). You can combine experience (Busi) with youth (Puig), physicality (Vidal) and a WC player (FDJ) in midfield. Vidal, Messi and Puig can interchange the positions depending on what Messi is doing (Vidal can drift into the ST position). We also have Fati, who is capable taking someone 1 on 1 and can help Alba in defense. Although we would depend on Semedo and Alba to provide some width, I think they are more than capable of that. Also they both NEED to play, because of Bayern's fast wingers.
And most importantly, with this lineup, we defend with 9 outfield players.
The only question for me here would be... Should we play Vidal or Roberto in RCM. But I would pick Vidal, because he can play ST and switch positions with Leo and Riqui occasionally.