JAMES Guy admitted he ran out of steam as he tried to force his way on to the podium in his opening event of the Rio Olympics.

The Radcliffe-born swimmer scraped into the final of the 400m freestyle yesterday but rose to the occasion in the final in the early hours of this morning before finally finishing sixth.

Guy, aged 20, went out hard to try to set the pace, but the world silver medallist at this distance faded as Australia's Mack Horton won gold in 3mins 41.55secs.

China's Sun Yang, the London 2012 champion and world gold medallist, was second in 3:41.68 and Gabriele Dettie of Italy was third in 3:43.49.

Guy, who finished almost a second outside his personal best in 3:44.68, will hope to do better in the 200m freestyle. He is world champion over four lengths.

"After 200 I felt mint," Guy said. "Then it hit me at 250. The speed's there, the endurance is there, I just didn't have that back-end speed today.

"The thing I realised today is that the World Championships is like halfway and the Olympics everyone steps up. That's what everyone did today."

He will go again later in the heats of the 200m freestyle, which start at 5.19pm British time.