Olympic champion Oussama Mellouli of Tunisia won the 5-kilometre open water race at the world swimming championships Saturday in Barcelona, Spain with an impressive finishing kick while Canada's Eric Hedlin took silver, 1.2 seconds behind.

Mellouli, who won the 10K at last year's London Games, sprinted past his rivals as soon as he got within the ropes outlining the finish area.

He clocked 53 minutes, 30.4 seconds.

Five-time world champion Thomas Lurz of Germany finished third, 1.8 back.

American takes 1st gold

American swimmer Haley Anderson won the women's open water race Saturday to take the first gold medal of the swimming world championships.

A silver medallist in last year's 10K Olympic race, Anderson edged Poliana Okimoto of Brazil in a sprint finish in the city's harbour.

Anderson finished in 56 minutes, 34.2 seconds while Okimoto took second 0.02 behind.

Another Brazilian, Ana Marcela Cunha, finished third.

The race took place in ideal conditions, with the water 24 degrees Celsius (75 Fahrenheit) and the air temperature between 28 and 29 Celsius (82 and 84 Fahrenheit).

Crowds lined the docks as the competitors swam alongside a line of moored boats and the port.