Brazilian Cesar Cielo's emotions again got the better of him on Saturday after he retained his 50 meters freestyle title to earn his second gold medal at the world swimming championships.

The Olympic champion and world record holder blasted down the length of the pool to clock 21.52 seconds. Italy's Luca Dotto won silver in 21.90 while Frenchman Alain Bernard, in lane eight, took the bronze in 21.92.

Cielo, who escaped a doping ban to compete here, broke down on Monday after winning the 50 butterfly and he wept again on Saturday in front of reporters and also had to choke back more tears on the podium.

"I wanted to win this one so badly. I am an Olympic champ and a defending world champ so I am really happy with the result," said Cielo.

"Coming to this world champs, gaining two golds and a fourth place (in the 100 freestyle), the results are better than what I had imagined two weeks ago."

Cielo was in danger of missing out on the championships before he escaped a doping ban just three days before the pool competition began.

The 24-year-old and three team mates tested positive for the banned diuretic furosemide in May but Brazil's governing body (CBDA) decided against banning the quartet.

Cielo said the positive test was caused by a supplement he took regularly that had become contaminated.

Swimming's governing body FINA appealed against CBDA's decision to the Court of Arbitration for Sport (CAS) and asked them to impose a three-month ban.

CAS, after a special hearing in Shanghai, ruled on July 21 that he would be allowed to compete because he took "sufficient precautions" over the supplements.

Cielo said the week had taken its toll but he felt better for it.

"Overall this world champs has been good for me," he added. "I feel I am a lot stronger right now."