Swimming-McIntosh motors to 400m freestyle crown, Australia revel in relay golds

July 27 (Reuters) - World record holder Summer McIntosh stormed to the women's 400 metres freestyle world title on Sunday, making a flying start to her bid for five individual crowns at the Singapore meet as American great Katie Ledecky finished with the bronze.

The highly anticipated battle between McIntosh and Ledecky failed to materialize as the Canadian led from start to finish and claimed the win in three minutes and 56.26 seconds, nearly two seconds ahead of Chinese silver medallist Li Bingjie.

Ledecky was 2.23 seconds behind McIntosh, who had only a small break before returning to qualify fastest for the 200 individual medley (IM) final in 2:07.39, less than two seconds off her world record.

"(I think being able to) mentally compartmentalise each race individually is a really important skill set that I've learnt over the past couple of years," McIntosh said.

Triple Olympic champion McIntosh is seeking to emulate Michael Phelps, the only swimmer to win five individual titles at a single world championships.

The 18-year-old Canadian may be hurtling towards greatness but a pre-teen Chinese swimmer showed she could be nipping at her heels in a few years.

All of 12-years-old, Yu Zidi qualified seventh for the 200 IM final in 2:10.22, shaving over four-tenths off her personal best in her world championships debut.

"I’m in? Oh. I’m happy about that, and I will continue to work harder," Yu said. "I hope to find a breakthrough at these world championships and show my potential."

Hailing from the northern Chinese province of Hebei, Yu made the swimming world sit up and take notice at national championships in Shenzhen in May by winning the 400 IM and 200 butterfly titles.

She also came second in the 200 IM in Shenzhen and is recording faster times than McIntosh did as a 12-year-old.

RELAY JOY

In the men's 400 final, Olympic champion Lukas Maertens won an absolute humdinger of a race, nosing ahead of Sam Short on the final lap and holding off the Australian by 0.02 seconds to claim his first world title in a time of 3:42.35.

Short won the event two years ago by the same margin from Tunisia's Ahmed Hafnaoui, with Maertens claiming bronze.

Australia finished the night celebrating a sweep of the men's and women's 4x100 freestyle golds.

Olivia Wunsch was the hero for the Australian women as she mowed down Torri Huske in the final lap to secure the gold in 3:30.66, 0.44 seconds ahead of the United States.

"I know there was a lot pressure on us this year but we all put in a great swim," said Australia's Meg Harris, who swam the second leg in 51.87.

"King" Kyle Chalmers then roared home in a scintillating anchor leg of 46.53 seconds to give Australia the men's relay gold in 3:08.97, 0.61 seconds ahead of Italy, with the U.S. finishing third.

"That's crazy. We've come together really well (during) this staging camp preparation. We believed we could do it and we did it," Chalmers said.

Earlier, American Gretchen Walsh, the silver medallist at the Paris Olympics, topped qualifying with Belgian Roos Vanotterdijk for the women's 100m butterfly final, both recording a time of 56.07.

China's former world champion Zhang Yufei was also safely through.

France's Maxime Grousset was fastest into the men's 50 butterfly (22.61) final ahead of Swiss Noe Ponti and Briton Benjamin Proud.

On Monday, medals will be handed out in the men's 50 butterfly and 100 breaststroke, as well as the women's 100 butterfly and 200 IM - where McIntosh will be the favourite.

Reigning Olympic men's 100 breaststroke champion Nicolo Martinenghi will compete in the final in Singapore after the Italian's disqualification in the semis was overturned.