We look back at 10 of the biggest heavyweight upsets in the sport's annals:

Dempsey v Tunney: Jack Dempsey was the greatest fighter of his generation and, despite Gene Tunney's previous impressive form, Dempsey was expected to beat the former US Marine in September 1926. Watched by 120,557 spectators, Tunney stunned the huge crowd and Dempsey with a points win in 10 rounds. Afterwards, Dempsey famously said to his film actress wife Estelle Taylor, "honey, I forgot to duck".