When Olympic champion Oussama Mellouli decided to accelerate during the 5-kilometre open water race at the world swimming championships on Saturday, the race was effectively over for his rivals.

The Tunisian surged ahead as soon as he got within the ropes outlining the finish area.

Mellouli clocked 53 minutes, 30.4 seconds. Eric Hedlin of Canada took silver, 1.2 seconds behind, and five-time world champion Thomas Lurz of Germany finished third, 1.8 back.

“I was hoping they wouldn’t stay with me,” Mellouli said. “Once I put the jets on I was able to take off, finish the race and take the win.”

Mellouli won the 10K and took bronze in the 1,500m freestyle at 2012 London Games to become the first swimmer to win medals in both the pool and open water at the same Olympics. And he won the 1,500 at the 2008 Beijing Games.

Mellouli had planned to retire after the London Games but he changed his mind a couple of months later, and only began training again six months ago.

“This year was supposed to be a year off for me,” he said. “So to come back here after a solid two months of training and to be on top of the world is quite exciting for me.”

Anderson shines

American swimmer Haley Anderson edged Poliana Okimoto of Brazil to win the 5km open water race.

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

Another Brazilian, Ana Marcela Cunha, finished third.

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