STEVE Clarke faces his most important test as Scotland manager in the Euro 2020 qualifier against Russia at Hampden tomorrow evening. Lose or even draw it and the national team's chances of reaching next summer's finals will be seriously, possibly fatally, damaged. A victory, meanwhile, will go a long way towards repairing the damage done by the defeat to Kazakhstan back in March.

Clarke has much to ponder ahead of the encounter with opponents who are second in Group I after four games. Not least in the midfield where he has several options. Here we examine the options he will be mulling over as kick-off approaches and look at what his possible starting line-up could be.

POSITION: GOALKEEPER

An easy decision for Clarke. He recalled the experienced David Marshall for the double header against Cyprus and Belgium back in June and the Hull City man, who moved to Wigan in the summer, repaid him with assured showings between the sticks. Scott Bain is out injured and his Celtic club mate Craig Gordon has just lost his place to Fraser Forster. Marshall has been in decent form at club level and will get the nod ahead of Jon McLaughlin of Sunderland and the uncapped Craig MacGillivray or Portsmouth.

SELECTION: MARSHALL

POSITION: RIGHT BACK

Stephen O’Donnell would appear to be the only option at right back for Clarke following the withdrawal of Liam Palmer earlier this week. Worked with the manager at Kilmarnock and was, the defeat to Kazakhstan in Nursultan aside, the first choice under his predecessor Alex McLeish. But could Ryan Jack, the on-form Rangers midfielder who has played the specialist role extensively in the past, be an option?

SELECTION: O’DONNELL

READ MORE: Former Rangers defender David Bates on the phone call from Steve Clarke that helped him get over Hamburg hangover

POSITION: CENTRE BACKS

With Grant Hanley and Liam Palmer pulling out of the squad and David Bates and Mikey Devlin being called in, there are four centre backs to choose from. Charlie Mulgrew is likely to be one of them due to his international experience. Could Liam Cooper of Leeds United partner him? Clarke made no secret of his admiration for the Elland Road captain, who has been overlooked by previous managers despite playing consistently well at club level down south, when he was appointed. Former Rangers man Bates did well in the Nations League wins over Albania and Israel last year. But he has only played one game for Sheffield Wednesday, against Rotherham last week, this season. Devlin is uncapped and it would be a surprise if he takes to the field.

Cooper and Mulgrew are both left-footed. But it wouldn't be the first time two "lefties" have played together at the heart of the Scotland rearguard.

SELECTION: COOPER AND MULGREW

POSITION: LEFT BACK

Andy Robertson of Liverpool. End of discussion.

SELECTION: ROBERTSON

POSITION: MIDFIELD

This is where Clarke will have his work cut out. He has an abundance of talented players who are plying their trade at a high level to choose from.

Scott McTominay has started for Manchester United in all four of their Premier League games this season and despite the Old Trafford club’s poor form that should see him get the nod. The nine times-capped 22-year-old is so adept at breaking down play and winning the ball back that he will be invaluable against quality opponents like Russia and Belgium. The national team are likely to spend long periods on the back foot against both sides.

Elsewhere, Callum McGregor of Celtic should take his place in the team alongside McTominay. He has been performing well for Celtic domestically and in Europe in recent weeks. His distribution is nigh on flawless. Clarke can ill afford stray passes gifting opponents chances. He also gives his team an added threat going forward and is capable of scoring.

After that, things get difficult for Clarke. He has to decide whether to go for John McGinn, Kenny McLean or Ryan Christie.

McGinn is adored at Aston Villa - he won their Players’ and Supporters’ Player of the Year award last season after helping them win promotion to the Premier League with a goal in the play-off-final – and started every league game for them last month. He brings energy, enthusiasm and physicality to their play. But he has made mistakes in his Scotland appearances in the past and has never quite managed to replicate his club performances with his country.

READ MORE: Scotland manager Steve Clarke delighted with 'ratty' Ryan Christie

Kenny McLean featured in the matches against Cyprus and Belgium and performed superbly. But he has only started two games for Norwich City this season – in a 4-1 defeat to Liverpool in the Premier League and a 1-0 loss to fourth tier Crawley in the Carabao Cup.

Christie, meanwhile, has arguably been the form player in Scotland this term. He has scored eight goals in 13 matches at home and abroad for Neil Lennon’s team. He was sensational in the Nations League wins against Albania and Israel last year before suffering facial fractures and missing the final games of the 201819 campaign. He would complement the deeper-lying McTominay and McGregor and assist whoever is selected in attack.

Clarke could look to the experience of Stuart Armstrong or Robert Snodgrass. But in all likelihood his central three will come from Christie, McGinn, McGregor, McLean and McTominay.

READ MORE: Robert Snodgrass is a big character who has returned to the Scotland fold under Steve Clarke

SELECTION: MCTOMINAY, MCGREGOR, CHRISTIE.

POSITION: FORWARDS

James Forrest, who has been on target six times in his last eight outings for Celtic, and Ryan Fraser, who has played in all five of Bournemouth’s matches to date, should, barring a change in tactics, be in the starting line-up. But who does Clarke play as his lone striker?

Does he put his faith in Oliver McBurnie? The Anglo became, for a brief spell, this country’s most expensive player when he moved from Swansea to Sheffield United for £20m this summer. He also opened his account in the Premier League with a well-taken goal against Leicester City last month. The 23-year-old, however, has still to open his account for his adopted homeland.

He also caused controversy last week when a film of him appearing to make derogatory comments about representing Scotland were posted on social media. The seven-times capped player spoke to his manager and squad mates this week to clear up the matter.

Or does Clarke look to Steven Naismith or Hearts of even Jonny Russell of Sporting Kansas City? Naismith is brilliant at leading the line by himself, bullying defences, holding the ball up, bringing others into play and is no slouch when it comes to putting the ball in the back of the net. But he has played less than 90 minutes of football this season.

Russell, who scored his first international goal against San Marino, also wouldn’t let him down. But the chances are McBurnie will get the opportunity to show what he can do.

SELECTIONS: FORREST, FRASER, MCBURNIE.

Scotland starting line-up to face Russia: Marshall, O’Donnell, Cooper, Mulgrew, Robertson, McTominay, McGregor, Christie, Forrest, Fraser, McBurnie.