#1 Marcus Rashford
It's highly possible that the reason Wayne Rooney has been in poor form and constantly under the spotlight is because of the emergence of Marcus Rashford. The 18-year-old has been in sensational form for the club ever since making his debut last season and has continued said form from the beginning of the current season.
Rashford has pace, the control and the composure when on the ball and seems to be the kind of player who already has the hearts of millions of Manchester United fans. He's been scoring for fun ever since Jose Mourinho drafter him into the first team and he's able to handle all the pressure that falls on his still-so-young shoulders.
United have had Rashford since he was a kid and it'll be for the best of everyone involved with the club if they get him to sign another long-term contract that keeps his income on a competitive level.