Katie Ledecky is on course to win a famous Olympic freestyle treble after claiming gold in the 200m in Rio.

The teenage American swimmer has already won the 400m freestyle and is the red-hot favourite in the 800m later this week.

Ledecky, 19, has taken her medal haul to three, having won 4x100m freestyle relay silver earlier this week.

Should she defend the 800m title she won as a 15-year-old at London 2012, she will become only the second woman to achieve the freestyle treble since fellow American Debbie Meyer completed the clean sweep in Mexico 1968.

Ledecky, world champion in the 200m, 400m, 800m and 1,500m freestyle, will attempt to complete full set when she goes in the 800m heats on Thursday with the final taking place on Friday.