Pereira is on-loan this season at Los Che.
He said of his relationship with United manager Jose Mourinho: "It was difficult because he told me I had to stay and I wanted to play and get more minutes.
"I never want to leave United but I want to play as well. In the end it will make me a better player and I will be that better player at United.
"I wanted to go somewhere and play a regular season.
"Last year I did it and I felt stronger for it. The United staff recognised it [in pre-season]."