Lacey's invitation to train with the senior team comes after he was named in England's Under-20 squad for the October international break. This is not the first time Lacey has trained with United's first team, as he first joined them at the age of 16 and has been consistently performing well in the Under-20s group.
Lacey is considered one of the key players who can help shape the future of Manchester United, and his inclusion in the senior team's training session suggests that Tuchel believes he has the potential to succeed at the top level.
England will face Wales in a friendly match on Thursday and Latvia in a World Cup qualifier next week. Rashford could feature in these matches after his impressive performances with Barcelona since the start of the season.
England's World Cup qualification is on track, with 15 points from six games so far. They could guarantee their spot in the World Cup this international break if they secure another point or two over the next week.