La Liga and the Super Cup only allow three non-EU players to be included in any matchday squad and Coutinho is registered with a Brazilian passport.
New signings Arturo Vidal of Chile and Brazilian pair Malcom and Arthur Melo all need to be on the non-EU visas, so the 25-year-old is set to switch to Portuguese registration.
Coutinho’s wife is Portuguese and the player is able to register as a Portuguese citizen after three years of marriage.
The Portuguese captain joined Juventus last month in a staggering €117-million deal after nine seasons in Madrid.
During his stint, the 33-year-old won four Champions League titles as well as two La Liga crowns in a trophy-laden spell.
But Ter Stegen insists their fiercest rivals will be a serious threat when the new season begins.
“I think they have an amazing team, like every year, just like us,” he said. “It’ll be equally difficult to play against them with or without Ronaldo.
“You have to understand that this is a player who made the difference in a lot of games, but we focus ourselves on our game and we know that, if we’re confident, we have the chance to do it all.”
The Frenchman made a £52million transfer from AS Monaco to the Spanish club.
The World Cup winner was officially presented at the Wanda Metropolitano and will wear jersey No11 at his new club.
Take a look at his official presentation, below.