Kosuke Hagino secured Japan's first gold medal of the Rio Olympics on Saturday with victory in the men's 400-meter individual medley final.

Hagino, 21, survived a late challenge from the USA's Chase Kalisz to win in 4 minutes 6.05 seconds at the Olympic Aquatics stadium.

Kalisz, who was the fastest in qualifying, finished seven tenths of a second further back and Japan's Daiya Seto was third in 4:09.71

It was Hagino's second Olympic medal after his bronze in the same even at the London 2012 Games.