Stephen O'Donnell is one of six Scotland stars who will miss tonight's pre-EURO 2020 friendly against Holland.
Che Adams, Grant Hanley, John McGinn, Nathan Patterson, David Marshall and 'Well star O'Donnell all failed to travel to Portugal for tonight's friendly as a precaution after John Fleck recorded a positive test.
Although all six players recorded negative tests and were allowed to travel, Scotland chiefs decided not to take any risks.
Bellshill man O'Donnell was set to feature in tonight's friendly and with Rangers star Patterson - the only other natural right-back in the squad - also missing, Clarke could play either James Forrest or Ryan Fraser at right-wing back.
The Scotland boss has only 19 players to choose from for tonight's friendly against Frank De Boer's side.
Clarke told Sky Sports : “Every time we come together I’m saying to the lads in training everybody is important and you never know when you’re going to be asked to play.
“Certainly in these uncertain times you never know when you are going to be asked to step up.
“Hopefully they can keep impressing – they’ve all impressed me so far in training.”
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