Tyler Clary of the United States swims in his men's 200m backstroke semi-final during the 2012 Olympic Games at the Aquatics Centre in London.

London - Ryan Lochte, conserving his energy for one of the most brutal challenges in Olympic swimming, safely navigated his way into the final of the 200m backstroke on Wednesday.

Lochte won his semi-final in a time of one minute, 55.40 seconds to qualify for Thursday's final second fastest overall behind his American team mate Tyler Clary.

Clary won his semi-final in 1:54.71, nearly seven tenths of a second ahead of Lochte but knowing he will have to be even faster in the final to hold off his team mate.

“The swim went really well. I hit most of the things I wanted to hit,” Clary said.

“There are a couple of things I want to work on for tomorrow, namely a couple of my turns and my breakout. I think tomorrow is going to be a pretty good swim.”

Lochte is the Olympic champion in the event and the clear favourite to win the gold but faces an extra challenge because he is swimming the 200 individual medley against Michael Phelps on the same days.

China's Zhang Fenglin was third fastest overall in the backstroke semi-finals, just ahead of Japan's Ryosuke Irie, who was runner-up to Lochte at last year's world championships. - Reuters