United States' Ryan Lochte competes in a men's 200m individual medley heat at the Swimming World Championships in Kazan, Russia, Wednesday, Aug. 5, 2015. (AP Photo/Michael Sohn)

KAZAN, Italy - Ning Zetao edged favourites Cam McEvoy and Vladimir Morozov to lead the 100-meter freestyle preliminaries at the swimming world championships on Wednesday — one of several strong performances by emerging Chinese competitors.

Ning won the penultimate heat of swimming's signature race in 48.11 seconds.

McEvoy, the top Australian with two-time defending champion James Magnussen out injured, won the final heat in 48.33. Morozov, the California-based Russian, qualified third in 48.46.

McEvoy placed eighth in the 200 free a night earlier.

"It's standard after any final you come up a bit flat in the morning," McEvoy said. "I've had a lot of practice being able to back up after a solid 200 program. ... The hardest part of this series is going to be the semifinal again, just like the 200. ... it's going to be very quick."

Olympic champion Nathan Adrian advanced safely in seventh while his American teammate, Jimmy Feigen, the silver medallist at worlds two years ago, failed to qualify.

"That was overall a little bit slower than we all expected it to be," Adrian said.

Ning swept the 50- and 100-freestyle titles at last year's Asian Games, becoming the first Asian swimmer to break the 48-second barrier. He entered this meet with the second-best qualifying time of 47.70.

Temperatures at the Kazan Arena were again on the cool side, at about 17 C (63 F). The temporary pool is set up inside a football stadium, and has a roof but the sides are open.

"It affects you, but there are things you can do to help that," Adrian said. "Wear a lot of clothes, wear a lot of layers, that way you can peel one off."

The 100 free semifinals were scheduled for later Wednesday, with the final on Thursday.

In the 200 individual medley, three-time defending champion Ryan Lochte of the U.S. led the way in 1:57.90. Daniel Wallace of Britain advanced second, and Wang Shun of China was third.

Hungarian veteran Laszlo Cseh, who already won a bronze in the 50 fly and is the leading qualifier for the 200 fly final later, did not start.

Lochte, the world-record holder, is an overwhelming favourite due to the absence of Michael Phelps, the three-time Olympic champion in this event. Phelps is sitting out the worlds after being suspended by USA Swimming for a second drunk-driving arrest.

Already known as perhaps the best underwater swimmer, Lochte is using a new rotating technique on the flip turns that has left swimming experts buzzing. Instead of rotating onto his stomach immediately after pushing off the wall, Lochte stays on his back for 10 metres, since he kicks better that way.

"I still haven't perfected it. The rotation, getting back on my stomach, it's just not there," Lochte said. "I've been three weeks into trying that turn, and I'm trying it out at world championships — probably not the smartest thing. I can see that it's helping. I just got to get it down.

"I'm 31 and a lot of people think at this age I can't learn anymore but it's not the case."

Lochte finished fourth in the 200 free, his only other individual event.

Fu Yuanhui of China led the women's 50 backstroke heats — which is not an Olympic event — in 27.66. Australia's Emily Seebohm, aiming for her third gold of the meet after her 100 victory a night earlier, qualified third.

Seebohm got to bed after midnight.

"I didn't feel fantastic when I woke up but I'm beginning to brighten a bit," she said. "Last night I loved every minute of it, and I wish I could go back and redo everything again. Well, maybe not the race, but everything afterward."

Another rising Chinese swimmer, 17-year-old Zhang Yufei — a winner of five medals at last year's Youth Olympics — topped the 200 butterfly heats in 2:06.92. Katie McLaughlin of the United States was second in 2:07.32, while Katinka Hosszu, the "Iron Lady" from Hungary, qualified sixth.

The American team of Ryan Murphy, Kevin Cordes, Kendyl Stewart and Lia Neal set a world record of 3:42.33 in the newly introduced mixed gender 4x100 medley relay. Australia, which didn't enter, established the previous mark of 3:46.52 last year.

Murphy's leadoff leg of 52.18 would have been good enough to win gold in the 100 back a night earlier but he wasn't entered in that event.

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Andrew Dampf can be followed at www.twitter.com/asdampf

News from © The Associated Press, 2015