Steve Clarke's Scotland side face one of the defining moments of their World Cup campaign when they take on Morocco in Boston on Friday at 23:00 BST, following their opening 3-point win against Haiti.

A draw would almost certainly be enough to secure a place in the knockout stages — a feat Scotland have never managed at a major tournament. A victory would seal qualification entirely and spare the nation a tense final group match against Brazil in Miami next Wednesday.

Back four or back five?

Goalkeeper Angus Gunn was largely untroubled against Haiti and looks certain to retain his place. The bigger question surrounds the defensive shape. Defender Scott McKenna missed the Haiti match through injury but has returned to contention, raising the prospect of a switch from a back four to a back five.

Former player Andy Halliday said on the Scottish Football Podcast that he fully expects a change of formation: "I think it will be either a 4-5-1, or do we actually go into that five at the back that Steve Clarke's deployed so often. I don't think we can give Morocco the amount of space that we gave Haiti and expect it to get a positive result at the end of it."

Does Christie return to the starting XI?

Clarke described leaving Ryan Christie out of the Haiti match as one of the hardest selection calls he has ever had to make. With Scotland struggling to hold possession — particularly in the second half — the Bournemouth midfielder could come back into the fold.

Scott Allan, a former Hibernian and Celtic midfielder, backed Christie's return on the Scottish Football Podcast: "I think Ryan Christie comes in just for his energy. We can't consistently give the ball away in the manner that we did against Haiti against a team like Morocco."

Who leads the attack?

Lawrence Shankland arrived at the tournament in fine scoring form after the friendlies against Curacao and Bolivia, but had a difficult outing against Haiti alongside Che Adams. Halliday suggested Shankland was the one who struggled most, making him the more likely of the two to be dropped.

Che Adams remains a firm favourite of Clarke's, as does Lyndon Dykes, who offers a more physical option as a lone striker. Ipswich Town's George Hirst has also been mentioned as a left-field option should Clarke want more mobility at the point of attack.

Former Scotland striker Duncan Ferguson, speaking to ITV Sport, argued the team needs a counter-attacking threat up front: "I'd maybe bring in one of the quicker players, maybe Hirst for instance, who's a bit more mobile than him. We just can't sit in and wait for a set-play."

With a place in the knockout rounds within reach, Clarke's selection decisions on Friday evening could determine whether Scotland finally write their name into major tournament history.