RIO DE JANEIRO - A new 100m freestyle Olympic champion was crowned on Wednesday, with Australian Kyle Chalmers winning the blue-riband sprint in 47.58 seconds.

Belgium's Pieter Timmers took silver at the Olympic Aquatics Stadium in 47.80sec. Bronze went to defending champion Nathan Adrian of the USA (47.85sec).

Australian Cameron McEvoy arrived in Rio as the favourite to win this event after clocking the fastest non-supersuit time of 47.04sec in April. But he finished seventh in 48.12sec.

Instead, it was Chalmers who ended Australia's 48-year wait for this coveted title. Mike Wenden was the last Australian to win this event, emerging victorious at the 1968 Games in Mexico City.

"It's hard being in this situation because I've been (racing) with a team-mate Cameron, who has looked after me all week and roomed with me," said the 18-year-old. "I don't want to celebrate too much because I know it would have been really hard for him tonight. But I'm sure towards the end of the week I'll be a little bit more excited."