Sophie Hitchon became the first British woman to win an Olympic hammer medal by taking bronze, as Pole Anita Wlodarczyk set a new world record to claim gold.
Hitchon threw a new British record of 74.54m on her final attempt to climb from fifth to third.
World champion Wlodarczyk, 31, threw 82.29m to break her own world record of 81.08m, while China's Zhang Wenxiu took the silver medal with 76.75m.
"I am over the moon," said Hitchon, 25. "I can't believe it."
Burnley's Hitchon, who finished fourth at the World Championships in Beijing last year, was in the bronze-medal position until the fourth round but fifth before her final throw.
When Moldova's Zalina Marghieva and Germany's Betty Heidler failed to improve, Hitchon took full advantage.
"You never know in hammer," added Hitchon, who was a ballet dancer for 10 years until the age of 14.
"The girls are all throwing really well. I didn't expect that I would hold third, I just wanted to throw further.
"It was just incredible to see the number three there and a national record, I couldn't be happier."
Michael Johnson, American four-time Olympic gold medallist:
"What you want to see is competition between the athletes and athletes responding to great competition.
"That's what Sophie did. It was really entertaining for fans to see that. It is what I think sport and athletics should be about."
Denise Lewis, British Olympic heptathlon gold medallist:
"Through the seasons, Sophie has been grafting, trying to iron out those chinks in the armour to make sure she was ready for this competition.
"It is simply, simply fantastic what she has achieved here. We love the big stars of the sport but what I love is when someone surprises us and delivers on the big occasion."
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