England Under-21s manager Gareth Southgate has revealed that Tottenham Hotspur defender Eric Dier asked to be left out of the squad to focus on improving at centre-back.

Spurs head coach Mauricio Pochettino has used Dier at right-back for the majority of this season due to Kyle Walker's long-term injury, but the 20-year-old is keen to prove his worth in the centre of defence.

In an attempt to continue his improvement, Dier elected to do extra training with Spurs rather than play in the friendlies with Portugal and France.

"It is an interesting one, we had quite a mature conversation about it and he feels there are parts of his game that he wants to work at," Southgate told reporters.

"Long term we both agree that he is unlikely to be a full-back and is going to be a centre-half. Without wishing Mauricio a problem, I think I agree with that so we said he will stay [with Spurs].

"It took me by surprise a little bit as he would have been in the squad and we thought he did well in Croatia, but he feels his time is best served on the training ground."

Dier's hopes of moving into the centre of defence were handed a boost on Wednesday with the news that Walker had returned to training with Spurs.