Manchester City have not yet registered Gabriel Jesus with the Football Association and he will not be eligible to play against Everton on Sunday.
City sources have indicated that the process is close to completion, but the FA is said to be awaiting paperwork from Brazil.
The final confirmation did not arrive before the registration deadline on Friday afternoon, meaning Jesus will have to wait to make his City debut.
The 19-year-old arrived in Manchester at the start of January and began training with his team-mates a week ago.
But while it is understood he has already conducted his first interview as a City player and that relevant photoshoots have taken place, his official unveiling is on hold until he is registered with the FA.
City will be hoping to finalise the process ahead of next Saturday's home game with Tottenham.