The West Brom striker has surprisingly got the nod to start ahead of Shane Long in Skopje tonight and his inclusion has certainly caused a stir.
So, just who is this relative unknown?
Cox is a 24-year-old front man who was born in Reading. He was with his hometown club from the age of nine to 20, but only made a handful of appearances. During his time there, he got to know Kevin Doyle, Stephen Hunt, and Shane Long.
Cox dropped down divisions to join Swindon in the January transfer window in 2008 and proved an immediate success.
A year and a half later, West Brom shelled out £1.5m for his services.
He qualifies for Ireland through a grandmother, who hails from Headfort, Co Galway, and let his availability be known last season when West Brom were on their way to promotion from the Championship.
Cox spent the first half of this campaign on the substitutes' bench, but got his chance in the Premier League when Roberto Di Matteo was replaced by Roy Hodgson.
He scored once in the top flight this term, a strike against Spurs from distance which made the shortlist for goal of the season.
The majority of his 19 Premier League appearances this term came with Hodgson in charge. He started eight of those matches.
His end-of-season form captured the attention of Giovanni Trapattoni, who brought him initially into the squad for last week's Carling Nations Cup.
He cancelled a holiday with friends in Spain in order to turn up and make an impression.
Cox caught the eye and scored on his debut in the 5-0 win over Northern Ireland. He then went on to play the duration of the 1-0 win over Scotland.
Ireland's latest international sang the Otis Redding song 'Sittin' On The Dock Of The Bay' as part of the tradition that squad newcomers must go through.