Stuart Armstrong captained Scotland Under-21s while at Dundee United

Celtic's Stuart Armstrong could earn his first full Scotland cap after Gordon Strachan named him in his squad for next month's Euro 2016 qualifiers.

The midfielder, 23, was previously in the full squad but did not play.

Derby striker Chris Martin and Hull goalkeeper Allan McGregor are back in the 26-man squad while Celtic striker Leigh Griffiths retains his place.

Scotland are away to Georgia on 4 September, three days before hosting world champions Germany at Hampden.

With all teams having played six matches, Strachan's team lie third in Group D with 11 points, three behind leaders Poland and two adrift of the Germans.

The Republic of Ireland have nine points.

Scotland's remaining Euro 2016 qualifiers Georgia (a) 4 September Germany (h) 7 September Poland (h) 8 October Gibraltar (a) 11 October

Strachan said of Armstrong, the only uncapped player in the squad: "I've been impressed for a while. I think it was two years ago he was in the squad.

"He has always been on the radar so it shouldn't come as a big surprise to anyone.

"He looks comfortable at the level he's playing, which I like, and he's becoming a major figure in games, which I like as well.

"It's dealing with the big-game mentality, dealing with the pressure and the crowds. It's something the boys at Celtic have to deal with all the time and Stuart is dealing with that well now."

Leigh Griffiths has impressed Gordon Strachan with his performances for Celtic

Strachan expressed his "delight" at having Blackburn's Grant Hanley back from injury, describing him as a "top" centre-half.

Pushed on whether he might opt to play Griffiths up front instead of Sunderland's Steven Fletcher, the Scotland manager replied: "Anyone who is in the squad, I must be tempted to play them.

"I look at their form, I look at them in the training and I look at who they are going to play against because every team has different weaknesses. You take all these things into consideration."

Strachan said he did not consider victory in Tbilisi to be essential to Scotland's qualification chances, but he warned it would be a difficult match.

"You never know when the real big game is, but it will be a tough game," he said.

"If anybody wants to know how Georgia are playing, look at a video of their last game - 4-0 (loss) against Poland but three goals came in the last six minutes, I think.

"Watch that video and you'll see how well they played in that game. From that we realised what a tough game it's going to be. We are under no illusions of that."

Scotland squad: Craig Gordon (Celtic), David Marshall (Cardiff City), Allan McGregor (Hull City), Christophe Berra (Ipswich Town), Craig Forsyth (Derby County), Gordon Greer (Brighton & Hove Albion), Grant Hanley (Blackburn Rovers), Alan Hutton (Aston Villa), Russell Martin (Norwich City), Charlie Mulgrew (Celtic), Andrew Robertson (Hull City), Steven Whittaker (Norwich City), Ikechi Anya (Watford), Stuart Armstrong (Celtic), Scott Brown (Celtic), Darren Fletcher (West Bromwich Albion), James Forrest (Celtic), Shaun Maloney (Chicago Fire), James Morrison (West Bromwich Albion), James McArthur (Crystal Palace), Matt Ritchie (AFC Bournemouth), Johnny Russell (Derby County), Steven Fletcher (Sunderland), Leigh Griffiths (Celtic), Chris Martin (Derby County), Steven Naismith (Everton).