The 22-year-old prospect was heavily involved throughout Tour 2018, presented by Aon, but the arrival of Lee Grant has facilitated a temporary spell away from Old Trafford in order to obtain regular first-team football.
It represents a second stint in the Primeira Liga after his previous success with Belenenses in 2016/17 and, as a Portugal Under-21 international, he will hope his performances promote his claims for a senior call-up.
Jose Mourinho is a firm believer in Pereira's talents and handed him a new contract in 2017 that runs until 2021, with the option of an additional year.