World Cup 2018: New faces add intrigue to unbalanced Scotland squad

Tom Cairney has been in scoring form for Fulham from midfield

Some players compelled Gordon Strachan to select them in his squad for the friendly against Canada and the World Cup qualifying tie with Slovenia.

Only 24 hours previously, Stuart Armstrong had been the most impressive performer during his time on the pitch in the Old Firm game, scoring Celtic's opening goal in the 1-1 draw.

Ryan Fraser, too, has performed impressively since establishing himself in the Bournemouth starting line-up and playing with more confidence and sharpness since becoming leaner and fitter.

Fulham midfielder Tom Cairney also could not be left out - and all three can make viable claims to be included in the starting line-up.

It might, though, be a frustration for national coach Strachan that they are all midfielders - the area of the team where he has the most strength in depth.

The squad continues to lack balance. There are three left-backs but nobody who is playing regularly at right-back.

Russell Martin and Ikechi Anya have both performed that position in the past, but the former currently plays at centre-back for Norwich City and the latter has started only two of Derby County's last five league games, one at left-back and one on the left of midfield.

Makeshift selections will need to be made, yet Phil Bardsley has played regularly for Stoke City at right-back.

Strachan has to find the balance between the dynamics and chemistry of his squad and the merits of individual players.

Defensive concerns

Bardsley, along with the likes of Ross McCormack, the striker on loan at Nottingham Forest from Aston Villa, and Stoke midfielder Charlie Adam, is a player the manager has been reluctant to select.

Central defence remains the critical area of concern, but Strachan will be relieved to call upon the experience and defensive nous of Charlie Mulgrew, who missed Blackburn Rovers' game against Norwich at the weekend but played 13 consecutive league games before that.

They have been at left-back, but Mulgrew played often enough at centre-back for Celtic and Aberdeen to be familiar with the role.

Strachan may want to retain a midfield core of Scott Brown, Darren Fletcher and Robert Snodgrass, who have all been influential for their club sides.

Matt Phillips (right) has scored five times for West Brom but has a hamstring problem

Matt Phillips, with four goals and eight assists for West Bromwich Albion, would have been a likely starter but has missed the last three domestic games with a hamstring injury.

Only six players have created more Championship goals this season than Newcastle United's Matt Ritchie - who has also scored nine - but Cairney is one of them and will be pressing for a place in the starting line-up.

There are familiar faces in attack, with Steven Fletcher joined by Steven Naismith, Chris Martin and Leigh Griffiths.

It is the return of Jordan Rhodes that is interesting, since he has been keeping Fletcher out of the Sheffield Wednesday team, with three goals and one assist in the league since he joined the club on loan from Middlesbrough in January.

On form, Strachan could refresh his starting line-up and not just the squad, since Mulgrew, Armstrong, Cairney and Rhodes can all make a strong case for inclusion.

The manager might opt to be more cautious, though, even if he admits the Slovenia game is one the national team must win to keep alive their fading hopes of World Cup qualification.