London 2012 Swimming: Lochte bests Phelps in semi-final showdown

Ryan Lochte may have helped Michael Phelps to a record-setting 19th Olympic medal, but he signalled Wednesday he won't be taking it easy on the Games great when they're in different lanes.

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Lochte beat Phelps in the first semi-final of the men's 200m individual medley, leading the way into Thursday's final in 1min 56.13sec.

With a comfortable lead he glided into the wall and Phelps' runner-up time of 1:57.11 was just the third-fastest of the semis behind the 1:56.74 clocked by Hungarian Laszlo Cseh in winning the second semi.

"It was a tough turn around," Phelps said of returning to the pool after earning a 200m butterfly silver and 4x200m free relay gold on Tuesday to surpass Soviet gymnast Larisa Latynina's career record of 18 Olympic medals.

His 19th came in the relay along with Lochte, Conor Dwyer and Ricky Berens and unleashed a stream of accolades that included a congratulatory tweet from US President Barack Obama.

Phelps said he was focused Wednesday on positioning himself for his defence of his 200m medley gold -- and perhaps conserve a little energy for the heats and semi-finals of the 100m butterfly.

"I am just trying to stay in the middle of the pool from now on," Phelps said.

He didn't manage that in his first event of these Games, the 400m medley. Swimming in lane eight, Phelps ended up missing out on a medal as Lochte notched a dominant victory on the opening day of swimming competition at the London Aquatics Centre.

With Phelps yet to claim individual gold in London, Lochte appeared to be in the drivers seat in the shorter medley, in which he is world champion and world record-holder.

"Ryan and I love racing each other," Phelps said. "Neither one likes to lose. I like to say we bring the best out of one another."

One thing in Phelps' favor is Lochte's tough double on Thursday night, when he'll also try to defend the 200m backstroke gold he won in Beijing.

Lochte won his 200m backstroke semi-final in 1:55.40, but American Tyler Clary's 1:54.71 in the second semi-final made him fastet heading into the final.

China's Zhang Fenglin was third-quickest followed by Japan's Ryosuke Irie, who is trying to improve on his bronze medal finish in the 100m backstroke.