Billy Gilmour was outstanding on his first full start for Scotland at Wembley.
But Scots boss Clarke challenged whoever came into the side in his place to seize their chance to help make national team history – and former Dundee United star Armstrong is the man charged with doing it.
Elsewhere, David Marshall has retained his place in goal, with Scott McTominay, Grant Hanley and Kieran Tierney in front of him.
John McGinn and Callum McGregor will line up alongside Armstrong in midfield, with Stephen O’Donnell and Andy Robertson at wing back.
Up front, Che Adams and Lyndon Dykes will reprise their partnership – and hope to turn chances into goals.
BREAKING: Scotland team named for do or die Croatia clash – and Stuart Armstrong comes in for Billy Gilmour
