Cesar Cielo Filho took a leap from sprinting obscurity on Saturday to claim Brazil's first Olympic swimming gold medal in the 50m freestyle.

Filho rocketed to an unexpected victory in the splash and dash in 21.30 sec, blowing away the field to win by 0.15, a sizable chunk in the sport's shortest race.

"I'm so so happy, I'm lost for words," said an excited Filho, who had never won a medal at the world level before and clambered on to the lane rope and roared when he realized he had won.

Cesar Cielo Filho of Brazil celebrates after winning the men's 50m freestyle swimming final at the National Aquatics Center during the Beijing 2008 Olympic Games August 16, 2008. [Agencies]

"I was so nervous before the race. I did it. It was my best race ever," added the towering 21-year-old, who broke down in tears on the victory podium and was mobbed by his Brazilian teammates on the pool deck after the medal ceremony.

Australian Eamon Sullivan and Frenchman Alain Bernard were favorites going into the Games having lowered the world record, which had stood since 2000, four times between them this year.

Frenchman Amaury Leveaux, who was also a strong contender, took the silver in 21.45. Bernard, the 100 freestyle gold medalist, was third in 21.49 with Sullivan an unexpected sixth.

Cesar Cielo Filho of Brazil swims in the men's 50m freestyle final at the National Aquatics Center during the Beijing 2008 Olympic Games August 16, 2008. [Agencies]

Filho's winning time at the Water Cube was just 0.02 shy of Sullivan's world record.

"Today was my lucky day. The sun shone on me. I'm so overwhelmed with emotion," added Filho, a business student at Auburn University in Alabama.

Born in Sao Paulo and nicknamed "Big Cesar", Filho has been impressive in the US collegiate scene and burst onto the global scene at last year's world championships in Melbourne, where he was fourth in the 100 freestyle and sixth in the 50 event.

He tied with American Jason Lezak for the 100 freestyle bronze on Thursday and now believes there is a lot of room for improvement and promised bigger things to come.

"I gave up a lot for this medal, I never saw my family, but the hardest things have gone before me," he said.

"I haven't yet achieved the time I am looking for. That's a secret and when I get it, I'll let you know.

"I will continue to struggle and work hard. This is the start of many things to come."

Agencies