Gareth Southgate has admitted that he may have called Mason Greenwood up too early in his career after the Manchester United youngster was once again omitted from the England squad.
The 20-year-old has not represented England at any level since making his senior debut against Iceland in September of last year.
Greenwood was subsequently sent home from that camp, along with Manchester City's Phil Foden, for breaching Covid-19 protocols and the bio-secure bubble at the team's Reykjavik hotel.
Southgate included Greenwood in England's provisional European Championship squad during the summer, only for him to withdraw through injury before the final cut.
The United forward also withdrew from the Under-21s Euros squad back in March and was omitted for September's senior and Under-21 internationals, despite a strong start to the season under Ole Gunnar Solskjaer.
Southgate said on Thursday that Greenwood's omission from this latest camp was due to a heavy workload, with Borussia Dortmund's 18-year-old midfielder Jude Bellingham also left at home for the same reason.
More than a year on from Greenwood's senior debut, the England manager also conceded that he may have been too hasty in calling up the young prospect.
"That's a fair challenge because we didn't know as much about him at that point," Southgate said.
"You're drawn by the quality of the performances and the maturity that you see on the field so you'd have to say that maybe that was a bit early because he's feeling at the moment to establish himself at Manchester United is a big challenge and I can totally understand that."
Southgate spoke with both Greenwood and Bellingham, their clubs and their families before making the decision to leave them at home for World Cup qualifiers against Andorra and Hungary.
Bellingham's omission was the most surprising of Thursday's squad announcement, after impressing in the 4-0 win over Andorra in September, but Southgate insisted that both he and Greenwood would have been selected if not for the need to manage them carefully.
"It is difficult sometimes because these boys are playing so well for their clubs and clearly we would like to pick them, there's no doubt," he said.
"We would like to have them with us in terms of do we think they deserve to be in on their performances, absolutely, but we want them to be big players for England for the long term and so we've got to try to make the right decisions as they're still physically growing.
"There's a maturation part of this, physically, and there's how much we expose them, and these are conversations that the boys are having with me and their families as much as the clubs. I've also got to listen to that because these boys want to play football, they want to play for England."
