In this context, the players who are starting the game.
Edit: For whoever gave me a minus for my answer, what would your suggestion be? "Convocação" might mean anyone who is listed on the roster for the upcoming game (that's just a guess based on how it can be used in Spanish). But I would never use "lineup" to refer to everyone on the bench along with the players on the field.
I think Duo is being too free with the translation here.
In this context convocação is rather nomination (of the player for the team) It’s indeed the calling of the players.
While line-up would be alinhamento. It’s the list of players who were nominated and made it into the team to play during a match or tournament.