 Marx took his international career to new heights on 7 October 2017, with his performance against New Zealand becoming much-talked about and publicised, arguably his best individual performance to date.The performances of Marx, as well as fellow forwards Steven Kitshoff and newly-appointed Springbok Captain Eben Etzebeth allowed South Africa to compete well against the All Blacks, with Marx making four turnovers and many tackles on defence, also setting up replacement loose forward Jean-Luc du Preez for a try and scoring the final try of the game.Marx's try was converted by Lions teammate Elton Jantjies to make the final score a narrow 24-25 loss to the All Blacks.