Australia have broken their own world record in the women's 4x100m medley relay final at the world championships at Rod Laver Arena in Melbourne.

The team of Emily Seebohm, Leisel Jones, Jess Schipper and Libby Lenton touched the wall in 3mins:55.74secs, slicing 0.56 seconds off the time set at last year's Commonwealth Games.

It is Australia's seventh gold medal of the world championships.

For Seebohm, 14, it is her first ever world championship medal while Jones, Schipper and Lenton have all already won gold this week in individual events.

The quartet remained under world record pace for the duration of the event, Jones putting the team into the lead after the USA opened a handy lead in Natalie Coughlin's opening backstroke leg.

From there the girls were never threatened, with Lenton racing home to the raucous support of a home crowd.

Seebohm is the new member of the team that set the previous record at the Commonwealth Games, replacing backstroker Sophie Edington.

Seebohm said she was ecstatic to win her first gold medal and break her first world record at such a young age.

"I could not be more proud of what I did and what our team did together," she said.

"I feel like I have gained a big experience."

Jones said it was the camaraderie amongst the team which helped lift the girls beyond the previous world record.

"Once you've got three girls responsible for, you lift even more just to get through," said Jones.

Lenton said the team had been aiming for the world mark, but breaking it was still beyond their own expectations.

"We hoped and wished for the greatest result possible which was a world record and gold medal but we all had to do our job as well as we could and it was an even better result than we could have hoped for."

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