Bernard Hopkins' career ended in undignified fashion on Saturday as the 51-year-old veteran was knocked out of the ring by Joe Smith Jr. at the Forum in California.

In the eighth round of Hopkins' 67th and final professional bout, he was sent tumbling through the ropes and onto the floor below by a flurry of punches from his opponent.

Hopkins had 20 seconds to return to the ring but, seemingly injured by the fall, failed to do so and was led away by his team.

Smith, meanwhile, was left to celebrate defending his WBC International light heavyweight belt, improving his record to 23-1, 19 of them by way of knockout.

For Hopkins, known as 'The Executioner', it was an unceremonious end to a long and storied career, which saw him become a dominant former champion of the middleweight division, while he was a world champion as recently as 2014, at the age of 49.

His knockout at the hands of Smith evoked memories of the famous end to the career of Joe Louis, who was knocked through the ropes by Rocky Marciano in his final bout at Madison Square Garden in 1951.