Marcus joined United on 15th August 2020, on a season-long loan from Nottingham Forest. The 21-year-old began his career with Arsenal before joining Barcelona, where he became the first Englishman since Gary Lineker to play for the Barca first team. After a loan at Dutch side Telstar, he moved to Nottingham Forest in January 2020, but the Covid-19 outbreak ended his chances of playing last season. His 2020/21 season was unfortunately cut short by an injury received in January, but nevertheless United signed him on a three-year deal in the summer of 2021.