RIO DE JANEIRO - World champion Mitch Larkin missed out on another golden opportunity to claim an Olympic title as American Ryan Murphy won the 200m backstroke crown on Thursday in 1min 53.62sec.

Australian Larkin finished second in 1:53.96, while Russian Evgeny Rylov took bronze in 1:53.97.

Larkin, the 100m and 200m backstroke world champion, was the favourite to win both races in Rio. But he was left in tears after finishing fourth in the 100m backstroke on Monday.

The two-lap race was won by Murphy, who has now completed a backstroke double at the Olympic Aquatics Stadium. He joins East German Roland Matthes and Americans John Naber, Rick Carey, Lenny Krayzelburg and Aaron Peirsol in achieving this feat.

"I remember looking up to all these guys, they were my idols so to think I could be that idol for some kid who is trying to do this is really cool for me," Murphy, 21, said.

"The 100 back is an event that comes a little more natural to me but the 200 back is one I really have to dig deep for so that was the event I was training all year for. That's the one I wanted really bad so I think this one means a little bit more to me."

He also extended US' dominance in the four-lap event. The last non-American swimmer to win the 200m backstroke at the Olympics remains Spaniard Martin Lopez-Zubero at the 1992 Barcelona Games.

"Obviously the goal this week was to try and win a gold but to realise I'm a silver medallist is pretty amazing," Larkin, 23, said. "There's always a disappointment and it will always be there but for me the silver lining is the learning curve that comes with it and that is just handling the pressure."