The former Dundee United star could be set to finally make his first appearance for Scotland, after being originally called-up in 2013.
Though Armstrong has been involved with the full Scotland squad before, being involved early in Strachan's reign, the former Dundee United star didn't quite get round to making his debut.
However, talking about Armstrong to the media as he announced his 23 players for the upcoming games against Georgia and Germany, ex Bhoys boss Strachan made it clear he has been a fan for some time.
"I've been impressed for a while. I think it was two years ago he was in the squad," the 58-year-old is quoted as saying by BBC Sport.
"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."
Armstrong has proved himself a vital part of Ronny Deila's side this season, starting eight of the ten available matches so far. The 23-year-old's attacking contribution could well be something that comes to the fore as he continues to settle at the club, with Armstrong scoring just once after moving from Dundee United last season, a figure he has already doubled this season after his double against St Mirren.
As with all Celtic players, the possibility of Champions League qualification would do his career no end of good should the Bhoys navigate their away leg to Malmo this week.