Under-21s head coach Tony Docherty is delighted with the buy-in from the three players who have dropped down from Scotland's senior squad.

Celtic right-back Colby Donovan, Udinese midfielder Lennon Miller and Heart of Midlothian striker James Wilson have all been included in a new-look Scotland Under-21 squad for friendlies against Ukraine and United States in Spain this month.

The three players were all in Sebastian Pocogonoli's first full Scotland squad and join Manchester United midfielder Tyler Fletcher, who went to the World Cup before joining Docherty's group in September.

"I'm really, really delighted with the introduction of the ones that have had that A squad experience and they're really the drivers," Docherty said.

"They become your leadership group that drives standards, create that mentality, get that identity.

"You've seen that in the last camp when I was out at the A squad camp and I returned with James and Findlay [Curtis] and then Findlay goes back up again as a result of his performance.

"Lennon and Colby Donovan, I've had dialogue with both of them quite a bit over the last couple of days, just to outline what their pathway is.

"If they're not going to be getting minutes for this camp with the A squad, it's important they come in to my squad and it will be a mirror image in terms of structure, fundamentals. And they just come in and get an opportunity to get game time."

Miller had hoped that last summer's transfer from Motherwell to Udinese would cement his place in the senior squad, but the 20-year-old finds himself in the area of the pitch with most strength in depth.

"I had a particularly long conversation with Lennon," Docherty revealed. "You've seen the example, the last camp there with Barney Stewart. He comes in, he scores three goals, he's in a good place when he gets back, gets into West Brom's first team, scores a couple of goals, they win a couple of games.

"I had a good conversation with Colby and he just wants to play. So it's important that we've got the buy-in. It's not us telling Colby, 'you're playing with the 21s', it's him in dialogue with us saying, 'I want to do that, I want to play and I want to impress'."

Meanwhile, St Mirren striker Eseosa Sule has been called up as Docherty prepares for a new European qualifying campaign after 16 of the 27 players from his first squad went beyond the age level.

Rangers youth forward Kyle Glasgow drops to the Scotland Under-19 squad for three European qualifying games.

The 16-year-old currently on loan to Alloa Athletic joins elder brother Euan Glasgow, who plays for Edinburgh City on loan from Hearts.

Goalkeepers: Sam Kane (Derby County), Rory Mahady (Leeds United), Aidan Rice (Dumbarton on loan from Celtic).

Defenders: Daniel Armer (Manchester United), Murray Campbell (Burnley), Colby Donovan (Celtic), Josh Dede (Middlesbrough), Mitchel Frame (Aberdeen), Dylan Smith (Ross County), Ethan Sutherland (Exeter City on loan from Wolverhampton Wanderers), John Tod (Dunfermline Athletic).

Midfielders: Calum Adamson (Raith Rovers on loan from Rangers), Aidan Borland (Accrington Stanley on loan from Aston Villa), Tyler Fletcher (Manchester United), Lennon Miller (Udinese), Calum McLeod (Inverness Caledonian Thistle), Kyle Ure (Crewe Alexandra on loan from Celtic), Dylan Watret (Ayr United).

Forwards: Findlay Marshall (Aberdeen), Alfie Stewart (Inverness Caledonian Thistle on loan from Aberdeen), Eseosa Sule (St Mirren), Andrew Tod (Dunfermline Athletic), James Wilson (Heart of Midlothian).