British heavyweight Anthony Joshua needed six rounds to stop boxing novice Jake Paul, who spent much of the contest in survival mode in one of the most striking mismatches in the sport's history.

Joshua, a two-time world champion, cut an increasingly frustrated figure as Paul danced around the ring for long spells, refusing to engage, before Joshua finally imposed himself by knocking down the YouTuber-turned-boxer twice in the fifth round.

Paul was down again in the sixth, before Joshua landed a powerful and clean right hand that brought a surreal night to an abrupt conclusion at Miami's Kaseya Center.

The American did not beat the count, although there was palpable relief inside the arena when he was able to rise to his feet and leave the ring without assistance on Friday night.