Katinka Hosszu of Hungary won the women’s Olympic 100 metres backstroke on Monday to claim her second gold of the Rio Games, edging out Kathleen Baker of the United States.
Canada’s Kylie Masse and China’s Fu Yuanhui tied for bronze, with the top four separated by just 0.31 seconds.
Australian world champion Emily Seebohm, swimming in an outside lane, set the early pace but Hosszu powered her way through the field in the last half of the race to touch the wall in 58.45 seconds.
Baker, who qualified fastest for the final, clocked 58.75, to finish 0.01 seconds ahead of Masse and Fu.
It was a second gold in Rio for Hosszu, the self-styled ‘Iron Lady’ of swimming, after her world record-breaking victory in the 400 individual medley on Saturday.
“It’s really cool, I can’t believe I’ve won the 100 back,” the 27-year-old told reporters. “I know I’ve done the 100 back in the 400IM a million times and the goal was to make it like second nature when I came to Rio, which is how it felt.
“This time I was fresh and in great shape. I just focussed on the execution and was not worrying about where I came.”
Hosszu, who is also swimming in the 200 backstroke, butterfly and medley, had come away empty-handed from three previous Olympics, despite winning five world championships titles.
Seebohm, silver medallist in London in 2012, had achieved the second-fastest time in the heats but qualified for the final in seventh.
She faded in the closing stages on Monday to finish seventh.
Missy Franklin of the United States, the 2012 Olympic champion at 100, was reduced to a spectator, having failed to qualify in the event for Rio at the US trials.
Franklin was in tears earlier after failing to make the final of the 200 freestyle, but has another chance in the 200 backstroke, in which she also won gold in London.

King beats Efimova to 100m breaststroke win
Doping tensions in Olympic swimming erupted after American Lilly King beat tainted Russian rival Yulia Efimova and US superstar Michael Phelps demanded life bans for swimmers with a drug record.
Booing broke out in the swimming arena on Monday as Efimova — twice convicted of doping but securing an Olympic place on a last-ditch appeal — lined up to challenge the women’s 100m breaststroke final.
King narrowly beat her then slammed her rival, stoking the controversy over revelations of Russian stated-sponsored doping.
“I think it just proved that you can compete clean and still come out on top,” King said of her win. She had also criticized Efimova before the race.
Clearly devastated, Efimova burst into tears after the race.
Phelps launched a broadside at drug abusers and encouraged others to speak out. Phelps said those punished for doping should face permanent exile from the sport.
“I think you’re going to see a lot of people speaking up more,” the all-time highest Olympic medal winner said.

Sun responds to drug taunts with 200M freestyle gold
China’s Sun Yang responded to Australian taunts about his doping history in emphatic fashion on Monday by winning the men’s 200 metres freestyle title to complete a golden Olympic treble.
Sun, who won the 400 and 1500 freestyle at the London Games, touched the wall in one minute, 44.65 seconds to beat South Africa’s Chad Le Clos by 0.55 seconds and become the first Chinese to win 200m gold.
Conor Dwyer of the United States won bronze.
Sun also won silver in Saturday’s 400 free and despite his delight at winning on Monday he still felt a twinge of regret that he was not celebrating his fourth Olympics title.
“I felt very sorry that I did not execute my responsibilities,” he said of the previous race. “In normal circumstances it should have been two gold medals (in Rio).”