The boxing world was shocked in what might be one of the greatest upsets boxing history after the Watford fighter was stopped in the seventh round.
Ruiz absolutely hammered the Brit on his debut, knocking him down four times over seven rounds.
Joshua went down twice in round three and twice again in round seven. It was at that point that the referee waved the bout off.
The shock loss means Joshua is stripped of his IBF, WBA and WBO heavyweight titles.