Michael Phelps wins his 20th Olympic medal with a dominant swim to beat compatriot Ryan Lochte in the men's 200m individual medley, BBC Sport said.

The American led from the front and looked as if he might break the world record but touched for a historic 16th gold medal in 1:54.27.

Phelps also becomes the first man to defend an Olympic swimming title twice, having won in Athens and Beijing.

Hungary's Laszlo Cseh was third, while Britain's James Goddard was seventh.