There were a host of clubs following him but he says Sir Alex Ferguson's charm made it an easy decision.
He told the Daily Mail: "United invited me to visit the academy with my dad and we met Fergie and he greeted me in Portuguese and that was very special. I didn't expect a 'Bom dia' from the manager of Manchester United, it made me want to sign immediately.
"I never wanted to go anywhere else."
Pereira is this season on-loan with Valencia.