Belgium international Lukaku, 26, has trained at his former team Anderlecht for the past two days, although Monday was a day off for United players.

Serie A sides Inter Milan and Juventus remain keen on the forward, who did not play in the Premier League club's pre-season matches because of injury.

In July, United rejected a £54m bid from Inter for Lukaku.

The Italian giants' manager Antonio Conte has previously confirmed the striker remains his number one target, saying: "I consider him a player who could improve our team."

Lukaku joined the Red Devils from Everton for an initial £75m in July 2017 and scored 12 league goals last season.