American Deontay Wilder will fight Australia's Jai Opetaia on the undercard of Tyson Fury v Anthony Joshua in December at Cardiff's Principality Stadium. Deontay Wilder will fight Jai Opetaia on the undercard of Tyson Fury vs Anthony Joshua at the Principality stadium in Cardiff on December 11. Next month's highly anticipated Tyson Fury vs. Anthony Joshua fight card on Netflix just got a big boost in star power.