The 17 year-old Portuguese attacker tasted first team football last season and Allen says he has the drive needed to make it at City.
"Last season, I saw Marcos, whilst training with the elite development squad, called over by the manager to train with the first team," Allen told the Manchester Evening News.
"The first team finished training and walked in, but Marcos came back to the elite development squad and continued to train with them.
"Then the EDS team finished and showered, and had lunch - and Marcos went to the gym. That is the level of focus, determination, drive and commitment you boys need to understand, to succeed at this football club."