An emotional Cesar Cielo upstaged a crack field to win Brazil's first-ever Olympic swimming gold medal in the men's 50 metres freestyle here on Saturday.

　　The 21-year-old Brazilian swam an Olympic record 21.30 seconds to beat home the French pair, Amaury Leveaux (21.45) and Alain Bernard (21.49).

　　Cielo reacted excitedly and leapt high out of the water when he his name flashed up as the winner.

　　"I'm very happy, I'm lost for words," Cielo said just after his momentous win.

　　"I was a bit nervous before the race but it was my best race ever. My dream was to be an Olympic champion and that is now realised."

　　Cielo broke down in tears as the Brazilian national anthem was played at the medal ceremony before he was embraced by his teammates.

　　Brazil had previously won three silver and six bronze medals in the pool at the Olympics.

　　Cielo's win broke a run of two American victories in the splash and dash race after victories by Gary Hall Jnr at Athens and a deadheat between Hall Jnr and teammate Anthony Ervin in Sydney.

　　Australian Ashley Callus was just outside the medals in fourth place in 21.62, but his world record holding teammate Eamon Sullivan was sixth in 21.65 and 0.35secs behind Cielo.