#2 Andreas Pereira
Pereira came back from a loan spell at Valencia last season and already looks a far better player now. He has matured well and has used the experience of La Liga to mold himself into a gritty playmaker.
He is technically sound and has excelled for United in the preseason, spraying passes, closing down opponents, showing maturity beyond his year. He is only 22, but he was the focal point of United's creative play in the preseason.
With Matic ruled out for at least a few weeks and other midfielders recovering from injuries or regaining fitness, this is Pereira's opportunity to make his mark.
His free kick goal against Liverpool in preseason was the stuff dreams are made of and United fans will be hoping for more of the same this season.
Mourinho should start him at every opportunity and allow him to develop into a better player. United will be competing in four fronts at least for the start of the season, so there will be enough opportunities for him to make his mark.
Mourinho needs to give him those opportunities because Matic is not getting younger and Pogba can be inconsistent at time, so Pereira would be a perfect fit for the United midfield in the near future.