Gordon Strachan says it was an easy decision to call up Callum McGregor to the Scotland squad for the first time in three years.

Questions were raised when the in-form Celtic midfielder was left out of his original squad for the 2018 World Cup qualifiers against Slovakia and Slovenia this week.

The club's top goalscorer this season also failed to be included for last month's six-pointer against Lithuania and Malta.

Injuries to key midfielders Scott Brown and Stuart Armstrong led to Strachan turning to McGregor at the weekend following his two goals against Hibernian in the Scottish Premiership.

"It was easy really," he said, when asked about his decision. "The people he is replacing are the same guys who sometimes keep him out of the Celtic team as well.

"There will be no embarrassment in being up against Armstrong and Brown, it's a strong squad they've got. They are strong in that area, like us, but he's kept his head down, plugged away and hopefully he feels it's a right big bonus coming away with us.

"There's a few unfortunate players in those central and wide midfield positions - it's not easy getting into the squad."

Strachan hinted Barry Bannan could be the man to step into the Scotland side, however, after being impressed with him in recent games.

The midfielder played in a more defensive role in Sheffield Wednesday's midweek defeat to Birmingham before moving forward for their 3-0 win over Leeds on Sunday.

"Barry's performance yesterday, in a position which was different to the one I saw him playing on Wednesday, he was further up the field and was excellent," he said.

"And he is somebody who turns up month in, month out and doesn't say a thing when he isn't picked. He just gets on with it and that's not easy at times.

"He can do things, he can see things, he has a good shot... but he'll probably want to add more goals to his game. If he does that he will be a heck of a player."

Strachan continued to praise everyone in the midfield role, saying the strength and depth in the area is key for him.

"There are many players left out from that area and probably wondering why," he continued.

"We've added Callum, who scored two goals at the weekend, we have John McGinn, who was fantastic at the weekend, and Bannan, who was magnificent with his team.

"It shows how strong we are and from there we could probably add another three or four midfield players."

He added: "Then you can rely on the players who have always done a good job, like Darren [Fletcher] and the two James' [McArthur and Morrison].

"And we have players on form as well, the newer ones are on form so that's good."