The Red Devils forward Romelu Lukaku will be penalized for not attending training without permission from the club.
The Belgian who his 26 years old, trained at Anderlecht, his former club for the past two days, although Monday was a day for the United players to rest.
Juventus and Inter Milan are still in pursuit for the forward, who did not participate in any of the pre-season matches Manchester United played due to injury.
Manchester United had rejected a £54m bid for Lukaku from Inter in July.
The Serie A giants’ manager Antonio Conte has previously approved the striker remains his number one favorite, saying: “I consider him a player who could improve our team.”
Lukaku joined Manchester United from Everton for an initial £75m in July 2017 and scored 12 goals in the 2018/2019 season