Steve Clarke's Scotland: Who could be the left-field call-ups?

Billy Gilmour has been praised during his short time in the Chelsea first team

Is it time for Steve Clarke to think outside the box?

On Tuesday, the head coach names his Scotland squad for the Euro 2020 qualifying double header with Russia and San Marino, having already admitted his side cannot now qualify for the finals as one of the top two in Group I.

Following the Hampden defeats earlier in September against the Russians and Belgium, he is now concentrating on the Nations League play-offs as their route to the finals.

Should Clarke experiment? Does he give uncapped players a chance? Will previously capped players who have fallen out of favour be back in the reckoning?

BBC Scotland takes a look at who the Scotland manager could consider.

'Amazing' Gilmour

Is it still too early for Billy Gilmour? The Scotland Under-21 midfielder has only played six minutes of Premier League football after making his Chelsea debut last month. He followed that, though, with what former Chelsea midfielder Cesc Fabregas described as an "amazing" performance in the Blues' 7-1 EFL Cup thrashing of Grimsby Town.

However, the 18-year-old, who has been a guest at Scotland senior squad training, went from earning the praise of the World Cup winner to finding himself out of the squad completely at home to Brighton & Hove Albion in the league on Saturday.

The additional problem for Clarke is that the former Rangers youth would have to squeeze someone out of the most competitive, and strongest, department of his squad - central midfield.

Aston Villa's John McGinn and Norwich City's Kenny McLean have scored in the Premier League in recent weeks, Manchester United's Scott McTominay has also impressed, including a stunning strike against Manchester United on Monday.

In-form Shankland

It has been reported Celtic and Rangers continue to monitor the progress of Lawrence Shankland, despite big clubs deciding against taking a punt on the striker as he moved from Ayr United to Dundee United this summer.

Could the 24-year-old be a left-field choice for Clarke as he looks for a front man to compete with recent incumbents Oliver McBurnie and Matt Phillips?

McBurnie has scored once in 10 appearances after joining promoted Sheffield United, while Phillips has four from 11 outings for West Bromwich Albion in the second tier.

Once Scotland's big hope, Oliver Burke's inability to win a place ahead of Phillips led to the 22-year-old being sent out on loan to La Liga outfit Alaves, where he has found himself mainly on the bench once more.

There were high hopes from there too for former Real Madrid youth Jack Harper after his summer move to Getafe from Malaga, but the 23-year-old is now back in the Spanish second tier on loan to Alcorcon.

With Hearts' Steven Naismith sidelined and Leigh Griffiths yet to make an appearance for Celtic since August, could Shankland be the natural finisher Scotland have been lacking?

Yes, his 15 goals in 12 appearances this season are with a second-tier side, but McGinn was in the Scotland squad while playing in the Championship for Hibernian.

Steven Fletcher is another to rediscover his scoring touch - and at a higher level than Shankland - his goal in Sheffield Wednesday's 4-1 win over Middlesbrough on Saturday being his fifth in 10 games. However, the 32-year-old said in the summer he was considering calling it a day on his 33 caps.

Even more left-field could be Fraser Hornby. The 20-year-old has made three starts in a row in the Belgian top flight for Kortrijk on loan from Everton, scoring in a 3-1 Belgian Cup win over Seraing.

The Tierney puzzle

A recall for Kieran Tierney would not be a surprise considering the 22-year-old's undoubted talent, but the timing might be.

Having been sold by Celtic while still recovering from injury, the left-back has only just made his Arsenal debut, in the 5-0 EFL Cup thrashing of Nottingham Forest on 24 September.

With Scotland having conceded 13 goals in their six games so far, with the only clean sheet coming away to San Marino, and Aberdeen's Scott McKenna and Hearts' John Souttar among the injury absentees, Clarke must be tempted to call on Tierney.

It would resurrect the selection puzzle that faced predecessors Gordon Strachan and Alex McLeish - does he use Tierney in a three-man central defence, or at right full-back, with captain Andy Robertson unlikely to be usurped at left-back?

With Hearts' Craig Halkett having picked up an injury on Saturday that means he could be sidelined for up to three months and veteran club-mate Christophe Berra being dropped to the bench, the options in central defence are dwindling yet again for Clarke. If he is looking for men in form, Motherwell 28-year-old Declan Gallagher could have caught his eye.

All will be revealed on Tuesday morning.