Anthony Ervin of the United States reclaimed the mantle of fastest man in the water on Friday by taking the Olympic 50 metres freestyle gold medal 16 years after he first won it, and by the slimmest of margins.

“I kind of laughed. It’s almost absurd I was able to do it again,” said Ervin of his immediate reaction to seeing his name with the number one against it.

France’s Florent Manaudou, the defending champion, finished second and just 0.01 seconds behind the 35-year-old veteran, who won in 21.40 seconds in a splash and dash down the pool.

Nathan Adrian of the United States took the bronze in the shortest and fastest race on the programme. He also finished third in the 100 freestyle on Wednesday.

The entire field was separated by just 0.68 seconds, with Ben Proud of Britain finishing fourth.

Ervin, at 35 the oldest swimmer to win a men’s individual gold, won his first title in a dead-heat in the same event with team mate Gary Hall Jr at the 2000 Sydney Games. Both touched out in 21.98 seconds.

He later sold that medal to raise money for relief efforts after the 2004 Indian Ocean tsunami.

Asked earlier in the week what he would do if he won another, Ervin had replied: “I don’t know. I’m living in the moment, man.”

Heavily tattooed, and as the oldest man on the US swim team making 31-year-old Michael Phelps look comparatively young, the Californian gave up competitive swimming in 2003 but returned for the 2012 Games in London.

Friday’s medal was his second gold from Rio, the first coming in Monday’s 4x100 freestyle. He also has a 4x200 freestyle silver from 2000.

“If anything, I was a little bit slower than I thought I was going to be,” he said.