Brazil's Cesar Cielo Filho triumphed in the men's 50 metres freestyle final at the world championships on Saturday to underline his superiority in the sprints.

The Olympic champion, who also took the 100 title on Thursday when he smashed the 47-second barrier with a world record, struck gold in 21.08.

‘I was expecting faster times. I'm very happy and very satisfied. I think the 100 took something out of me but I haven't reached my peak yet,’ he told reporters.

France's world record holder Frederick Bousquet was second with compatriot Amaury Leveaux third.

Leveaux heard during the championships that his father had died.

‘The last few days were not easy,’ he said before the race. ‘I didn't know if I should stay or leave. I decided to stay for my family.’

Earlier at the meet, Australia's Marieke Guehrer sprang a surprise by winning the women's 50 metres butterfly final.

She glided through the water in 25.48 seconds with China's Zhou Yafei second and Norwegian Ingvild Snildal taking bronze.

‘It was a surprise. I just wanted to go in there tonight and swim the best that I can. I didn't care where I came,’ the Australian told reporters.

Sweden's 2007 champion Therese Alshammar, who swam a world record 25.07 in Friday's semi-finals, finished fourth with fellow contenders Magdalena Veldhuis and Sarah Sjostrom only managing fifth and sixth respectively.