Rangers full-back Nathan Patterson and Leeds winger Liam McCarron have been called up to the Scotland U21 squad.
The U19 internationals have been promoted into Scot Gemmill's U21 set-up ahead of the European Qualifier against Lithuania in Vilnius on September 8.
Patterson, 18, came off the bench in Rangers' Europa League defeat by Bayer Leverkusen this month to make his second appearance for the club.
McCarron, 19, made 20 first-team appearances for Carlisle before signing for Leeds last summer but is yet to feature for the Premier League newcomers.
Midfielder David Turnbull and his former Motherwell team-mate, James Scott, who is now with Hull, are both back in the squad following injury.
Defender George Johnston, fresh from making his Feyenoord debut, and Stade de Reims striker Fraser Hornby, are also included.
Chelsea midfielder Billy Gilmour drops out after undergoing knee surgery.
Scotland U21 Squad: Ross Doohan, Robby McCrorie, Kieran Wright, Daniel Harvie, George Johnston, Lewis Mayo, Ross McCrorie, Tom McIntyre, Nathan Patterson, Ryan Porteous, Allan Campell, Dean Campbell, Lewis Ferguson, Stephen Kelly, Lewis Smith, David Turnbull, Fraser Hornby, Liam McCarron, Connor McLennan, Glenn Middleton, James Scott.