A place in history is at stake as the national side attempt to qualify for the knock-out phase of a major tournament for the first time ever.
Scotland will progress to the last 16 if they claim the three points in their final Group D fixture, which will be easier said than done againt a Croatia side who were World Cup runners-up only three years ago.
Clarke’s biggest selection dilemma centred around replacing Billy Gilmour, a stand-out in the 0-0 draw at Wembley on Friday, who is ruled out after being placed into self-isolation following a positive Covid test on Monday.
Here is the starting XI he has selected for the biggest match the country has faced in decades ...
5. LWB - Andy Robertson
Two excellent showings from the captain so far in the tournament - a third is crucial if Scotland are to have any chance of progress. Photo: CARL RECINE
6. RWB - Stephen O'Donnell
To say he went from zero to hero would be a little harsh but should be riding the crest of a wave after an outstanding display against England followed a maligned performance in the opener. Will be tasked with keeping dangerman Ivan Perisic quiet. Photo: JUSTIN TALLIS
7. DMC - Callum McGregor
After a brilliant shift against England, same again from McGregor is required to shackle Modric and keep Scotland ticking. Looked back to himself at Wembley and one more busy shift could push Scotland over the line. Photo: PAUL ELLIS
8. DMC - John McGinn
After being shackled by the Czechs he stepped up against England - as they all did. Scotland's driving force will again have the nation's expectations on him for some more Hampden magic. Photo: CARL RECINE