After a two-month training camp and three warm-up Test matches, the audition process is over and Scotland head coach Gregor Townsend must decide which 31 men to entrust with the nation's hopes at the World Cup in Japan next month.

Townsend announces his squad on Tuesday and, while many could be considered stick-ons, there are a few marginal calls for the coaching team to make.

Who takes the third hooker spot? Will three or four locks go? Could Townsend gamble on taking just one out-and-out number 10? Which centres will make the cut in the most competitive area of the squad?

BBC Scotland looks at the big selection calls facing Townsend.

Front row

The props look to be fairly straightforward picks, with Willem Nel and Zander Fagerson likely to be fighting it out for the starting tight-head spot, while Allan Dell is the prime candidate for the loose-head position.

Simon Berghan, normally deployed at tight-head, made a brief cameo at loose-head during the defeat by France in Nice. That suggests Townsend is likely to take only five props with Berghan as back-up cover on both sides of the scrum, meaning Gordon Reid and Jamie Bhatti will battle it out for the remaining spot.

Scotland's two frontline hookers by some distance are Stuart McInally and Fraser Brown, who will both go to Japan, even allowing for Brown's lack of action due to foot injuries.

The third hooker spot is slightly more intriguing. George Turner has been the third-choice for quite some time, but the emergence of Glasgow's Grant Stewart has given Scotland a fresh option. Townsend is a fan of Stewart's athleticism around the park, but Turner's greater experience may just get him the nod.

Second row

Grant Gilchrist and Jonny Gray are two experienced campaigners who are certain to travel to Japan. Ben Toolis' form had dipped slightly after an excellent 18 months for club and country, but a good display, including a first Test try, against Georgia should seal his place at the expense of Scott Cummings.

With Sam Skinner ruled out through injury, it could be left to Blade Thomson to offer lock cover ahead of Tim Swinson.

Back row

Some difficult decisions for Townsend here. The experience and class of John Barclay and Hamish Watson make them shoo-ins, while Thomson's ability to cover lock, blindside and number eight makes a compelling case for inclusion, assuming he has sufficiently recovered from the concussion symptoms arising from a head injury suffered against France.

Ryan Wilson is a Townsend favourite and, while he has struggled to produce his best stuff in the past year or so, 44 Tests worth of experience should carry enough weight to get a seat on the plane.

Jamie Ritchie impressed after breaking into the team amid a huge injury crisis in the Six Nations and is equally effective at six or seven. If he makes it, that leaves Magnus Bradbury, Josh Strauss and Matt Fagerson battling for one spot.

Strauss on form is Scotland's most destructive ball-carrier, but the issue is that best form has only ever been seen fleetingly. His tendency to drift out of matches is a problem and there is a sense he has used up all his chances to make himself indispensable.

Fagerson impressed in the victory in Tbilisi, but although injury prevented Bradbury featuring in any of the three warm-up matches so far, his instrumental role in Scotland's famous fight-back at Twickenham in March will remain fresh in Townsend's mind. Like Strauss, he needs to bring greater consistency to his game, but Bradbury's sheer size and power may make him the favoured option.

Scrum-half

The head coach's most straightforward selection. Greig Laidlaw and Ali Price will vie for the starting nine jersey for the World Cup opener against Ireland, while George Horne provides a quality third option to step up when required. No other horses in the race.

Fly-half

Finn Russell is Scotland's undisputed king at fly-half and absolutely integral to their hopes of making a mark in Japan. Adam Hastings is the natural understudy, but does his lack of form leave him vulnerable? There will be at least two, probably three, players in the squad outside Russell who can cover 10 if required. The likelihood, though, is travelling with just one out-and-out 10 is just too big a risk and Hastings will make it.

Centre

The most competitive area of the squad and the most difficult to whittle down. The big casualty here could be Huw Jones. When he was tearing England apart in the Calcutta Cup win in 2018 to continue his red-hot start to his Test career, the notion of him not making the World Cup squad would have been ridiculous. His form has fallen off a cliff since then and you wonder how much longer Townsend can wait for him to find his best stuff. Time may already have run out.

Sam Johnson looks to have picked up where he left off after an impressive Six Nations and will go. Duncan Taylor is a player Townsend holds in the highest regard and, now he seems to be free of his desperate injury problems, it is hard to see him being left out, especially as he provides options from 11-15.

Rory Hutchinson has made a superb start to his international career, including two tries against Georgia, and looks to have timed his run perfectly. He can also cover all three midfield positions.

Peter Horne has been part of many of Scotland's best days in recent times. But, with so many other centres playing well, his place is not assured and his ability to cover 10 is not quite the trump card it may have been previously with Hutchinson able to offer even greater flexibility.

Townsend values Chris Harris' defensive nous and his try against France came in a display in which he finally looked at home in the international arena. Another one who can cover on the wing, but how many utility players do you need in the squad?

With Hutchinson making such an impact, it could be a 50-50 call between Horne and Harris for the final midfield spot.

Back three

Stuart Hogg is already written in ink for the 15 jersey in the World Cup opener against Ireland and Sean Maitland will not be far behind on the left wing. Tommy Seymour, while possibly not in the best form recently, is a proven performer and his combination with Hogg and Maitland is Townsend's favoured option.

Darcy Graham has taken to Test rugby like a duck to water, bringing a different style to the other wings with his ferocious ball-carrying. And he knows his way to the tryline. It would be a major surprise if he doesn't make the 31.

Graham and Maitland can both cover full-back, which makes Blair Kinghorn slightly vulnerable, but the odds are on him travelling, with Byron McGuigan being the odd man out.

Captain

There are three contenders for the captaincy - McInally, Barclay and Laidlaw.

All have done the job before, but McInally is the man in possession and led the side in Georgia, with Laidlaw also starting.

The Edinburgh hooker is also the only one of the trio guaranteed to start against Ireland if fit, but Scotland are blessed with proven leaders to step in when required.