Gold medallist Ryan Lochte (R) of the U.S. poses with his compatriot silver medallist Michael Phelps after the men's 200m individual medley. (DAVID GRAY/REUTERS)

After losing to Ryan Lochte earlier this week, Michael Phelps unwittingly stamped an asterisk on any victory Lochte achieved over him at these swimming world championships. Phelps said he wasn’t in top form. He vowed to go faster at the London Olympics next summer. When asked about Lochte’s excellence, Phelps talked about his own failures.

Lochte showed no annoyance, but he found the perfect way Thursday night to short-circuit the skepticism about his place in the sport, the doubts about whether he could conquer a super-fit Phelps.

Lochte didn’t merely defeat Phelps for the second time this week in the 200-meter individual medley in front of a stunned crowd at the Oriental Sports Center, he also set a world record — the first in a 50-meter pool since polyurethane speedsuits were banned two years ago.

“I just wanted to do something that everyone thought was not possible,” Lochte said. “All the hard work I’ve done this year has definitely paid off.”

Lochte took the lead after the first butterfly leg and held on as Phelps closed in the waning meters, touching the wall in 1 minute 54 seconds flat — 0.10 faster than the world mark he set at the 2009 world championships in Rome.

Phelps finished in 1:54.16, a personal best that went under the 1:54.23 he swam at the 2008 Summer Games. The silver medal left Phelps temporarily at a loss for words — he uncharacteristically declined to speak with reporters immediately after the race, delaying his comments until the formal news conference that always follows the medal ceremony. He later apologized, admitting he needed time to collect his thoughts.

“I thought I had it on the last stroke,” Phelps said. “I felt myself gaining and gaining and gaining. It is what it is. I fell short. I think that race will provide a lot of motivation for the next year. . . . There is lots of frustration going through my head.”

The pair swam side-by-side in lanes 4 and 5 and quickly left the field behind. Hungary’s Laszlo Cseh, the silver medalist at the ’09 world championships and ’08 Olympics, came home in 1:57.69 — 3.69 seconds behind Lochte.

“I think you watched the two best IM swimmers ever swim tonight,” said Lochte’s coach, Gregg Troy. “I think you got a real treat . . . I don’t know if we’re going to call a few hundredths of a second passing Michael Phelps, but it puts us in a good lead.”

Phelps, who has earned one gold medal, two silvers and one bronze here, has one remaining individual event, the 100 butterfly. But his week will be remembered for his failure to win in two head-to-head races with Lochte, who has emerged as a major challenger to Phelps’s international dominance.

Phelps, however, continued to look inward rather than across the lane lines.

“He’s really just done all the little, small things right,” Phelps said. “He’s super-focused right now. You can see that. He’s putting races together that are helping him to win. To be honest, I think he’s more prepared. . . .

“To be able to go faster than he went in 2009 is, I think, incredible. [But] I didn’t win because I wasn’t as prepared as I should have been.”

Lochte, who later posted the fastest time in the 200 backstroke semifinals (1:55.65), shrugged off Phelps’s assessment of the race.

“That’s his call,” Lochte said. “I can’t really comment that much about it. You’re either ready or you’re not. If he says he wasn’t ready, I guess he wasn’t ready.”

Lochte, who won four medals at the 2008 Summer Games and six golds at last year’s Pan Pacific Championships, was ready. U.S. teammate Tyler Clary claimed after the race that he had predicted the very time Lochte laid down. He said he had been kidding with Lochte and told him: “Why don’t you stop being a big baby and go 1:54 like you should?”

Added Clary: “He looked at me like I was crazy. . . . He’s having an incredible year.”

On Tuesday, Lochte chased Phelps down in the 200 freestyle after Phelps took the lead at the halfway point. On Thursday, Phelps swam the last 50 in 27.36 — .13 faster than Lochte — but finished with a long stroke that might have cost him.

“I thought the last stroke was the stroke I needed to take,” he said. “I probably could have rushed. . . Maybe I would have gotten to the wall faster.”