Reis will be tested on whether he can take the main position as Manchester City's center back from Dias. Manchester City's formation for the time being is different from usual. It appears Pep Guardiola is using a 4-1-4-1 formation. One player placed above the center-back is Reijnders who is usually Rodri's position. There could be a change in formation later.
There is another possibility that a number of main players such as Haaland, Silva and other names are reserved because the team to be faced is Wydad Casablanca, a representative from Morocco.
The formation used by the opponent is 5-4-1, clearly they know how strong Man City will be, who will dominate the midfield with the formation applied by Pep at this time. Indeed, something different and rarely done by Pep with the current formation, but everything will change when the players who are now on the bench will enter. Maybe in the second half, but Pep might test some players who were fielded from the beginning of the first half. We will see how efficient the tactics and formation applied by Pep are in this match.