Scotland are up against it in World Cup Qualifying. Dismal results in their group so far leave them second bottom and at risk of outright elimination if they lose this Sunday's match at home to Slovenia.

Qualification is a massive long shot regardless and after Wednesday night's draw with Canada the pressure is on national boss Gordon Strachan to start delivering results and show improvement.

At the heart of his squad to face Slovenia are six Celtic stars who are having the season of their lives under Brendan Rodgers. The form of the Scottish champions is incredible and historic, so it's no surprise Strachan has called upon some of Rodgers' most important players.

However, while including them in squads, Strachan has shown a reluctance to play many of them in the past, often opting for players who ply their trade in England in the Premier League and Championship.

Here are the THREE Celtic players the Scotland boss simply must rely on to bail him out of a tricky situation...

Leigh Griffiths

Many thought that Leigh Griffiths would start against Canada at Easter Road on Wednesday but he was snubbed again by Gordon Strachan, not featuring until being brought on from the substitute's bench in the second half.

Even in Griffiths' incredible 40-goal campaign last season, Strachan often preferred to go with the likes of Chris Martin and Steven Naismith ahead of the in-form Celtic striker.

Surely now though is the time to unleash him at Hampden. Scotland aren't exactly blessed for goalscoring strikers right now and although Moussa Dembele is ahead of him in the Celtic pecking order, when asked Griffiths has always delivered for the Hoops.

He hasn't scored for his country before but then again, he's had little opportunity from the start. Is this the weekend Griffiths announces himself on the international scene with a goal?

Stuart Armstrong

Stuart Armstrong hasn't won a single Scotland cap and is enjoying only his second call-up to the squad. The midfielder is being rewarded for a terrific season at Celtic, a vitally important part of Brendan Rodgers' set-up.

His inclusion should go further than simply joining up with the squad though; he should start against Slovenia at Hampden and be allowed to show what he can do at this level.

At 24 years old he has the experience to cope with the occasion, especially after matches in the UEFA Champions League earlier this season.

If deployed correctly he could be an exciting and dynamic force in the Scotland midfield and be the important link between engine room and attack. It's the strongest area of Scotland's squad but if Strachan puts his trust in the former Dundee United man then he's likely to reap the benefits.

Kieran Tierney

Still just a teenager, it speaks volumes about the quality and potential of Kieran Tierney that he already has Scotland caps and isn't part of the country's U21 set-up.

The Celtic left-back is having another stellar season with his boyhood heroes, almost ever present in Brendan Rodgers' first team when fit and available.

His tireless running, tackling and ability to combine with teammates in the final third make him an excellent option for Strachan to call upon this Sunday.

Lee Wallace showed he is not up to the task of international football on Wednesday after a dismal performance against Canada and Tierney is likely to be fighting it out with Andrew Robertson for a start this weekend.

If Strachan goes with Tierney though he'll at least get one of the most committed performances on the pitch and a player who everyone knows can rise to the big pressure occasions.