World-record holder Zhao Jing led China to gold and silver double in the women's 50m backstroke final at swimming's world championships on Thursday with teenage compatriot Fu Yuanhui finishing second.

The 22-year-old Zhao, who won 100m backstroke gold at the 2011 world championships, clocked 27.29sec in the sprint with 17-year-old Fu at 0.10 back and Japan's Aya Terakawa 0.24 adrift in bronze.

Having finished fifth in the Olympic 100m backstroke final, with the 50m being a non-Olympic event, Zhao said she had wanted to bounce back from her London 2012 disappointment.

"I feel very happy to have proved myself and taken the gold medal," she said.

"After the Olympics I had some injury problems and my performance dipped so that is why I think I have proved myself again.

"It has been down to my hard work and dedication.

"The hardest competition is the Olympics and I feel that I let myself down there, so I wanted to come back and prove himself here."

Zhao admitted she was some way short of the full fitness which saw her set the world record of 27.06 four years ago at the 2009 Rome world championships.

"I was not in good condition some months ago, I felt it in the heats and semi-finals," admitted Zhao.

"Before the final, my coach gave me confidence and encouragement to get better, I want to thank him."

Teenager Fu said she was delighted as China collected their fourth swimming medal of these world aquatic championships after Sun Yang's freestyle victories in Sunday's 400m final and Wednesday's 800m final.

"I am very happy to see China get another gold medal," she said.

"I made some mistakes, because of my lack of experience, but I will learn.

"I had no experience of such a big competition, so I am happy to get such a result.

"I have the upmost respect for Zhao Jing and what she has achieved."

Japan's Terakawa, who collected her second bronze in Barcelona after third in Tuesday's 100m backstroke final, said she was disappointed.

"I came to win the gold medal, so I am a little bit disappointed, but I really did my best in the pool and I enjoyed the final. I had a really good start, but it wasn't enough.

"It is the first time I got two medals at an international competition so I am happy with that although I wish the colours were different.

"In 2003, I competed in Barcelona as well and then I didn't make the semi-finals or finals.

"Back then I didn't expect that I would still be swimming now, so I'm happy to get a medal.

"Today I was speaking with Zhao and she said she was old, but she is only 24 and I am 29!

"I hope I can give encouragement to older swimmers."