Michael Phelps has smashed every record in the modern Olympics, that historians have began to compare the American swimmer to stars of the ancient Olympic Games.

The 31-year-old won his 21st Olympic gold medal in the early hours of Wednesday morning, when he won the 200-metre butterfly final. That win was Phelps' 12th individual title.

He is now level with Leonidas of Rhodes as having won the most individual Olympic titles. One more win will break the record that has stood since 152 BC.

#Olympics With his 12th individual Olympic title Michael Phelps equal the all time Olympic record set by Leonidas of Rhodes in 152 BC

— Hilary Evans (@OlympicStatman) August 10, 2016

Leonidas won the stadion, the diaulos, and the hoplitodromos in four consecutive Olympics between 164 BC and 152 BC. The three races are the ancient equivalent of the 200-metres, the 400-metres and the 400-metres with heavy armour.

The hoplitodromos involved running from one end of the Olympic stadium to the other, and back, whilst wearing bronze armour and carrying a sword and shield. The other events would have been competed in, while athletes were naked.

Phelps has two more chances to break the record. He has still to compete in the 200-metre individual medley and the 100-metre butterfly events.

It would be a fitting way to end his Olympic career.