Almaz Ayana stunned the crowd at Rio's Olympic Stadium on Friday, smashing the 10,000 metre world record to claim the Games' first athletics gold.
On the opening day of track and field action, the Ethiopian blew away the remainder of the field, crossing the line in a time of 29:17.45, taking more than 14 seconds off the previous best set by China's Wang Junxia in 1993.
The likes of David Rudisha and Jessica Ennis-Hill were also in action, as they began their respective defences of the 800m and heptathlon crowns.
AMAZING AYANA MAKES HISTORY
Ayana pulled away from the competition around the halfway mark and, with no-one able to stay with her, the 5,000m world champion romped to a remarkable triumph.
Kenya's Vivian Cheruiyot took silver, while double defending champion Tirunesh Dibaba completed the podium.
Great Britain's Jo Pavey, competing in her fifth Olympics at the age of 42, finished 15th.
HEARTACHE FOR HARTING
Four years ago, Robert Harting claimed discus gold and promptly celebrated by stripping down to his waist and jumping the hurdles.
There will be no repeat scenes of elation this time around, though, after the 31-year-old German failed to qualify for the final, his best effort of 62.21m proving insufficient.
It was not all bad news for the Harting family, though, as Robert's younger brother Christoph sealed his place with a throw of 65.41m, the best in his group.
RUDISHA ISSUES WARNING
David Rudisha stunned the crowd at London 2012, setting a new world record of 1:40.91 in romping to 800m gold.
The Kenyan began his defence of that crown on Friday, easing to victory in the third heat in a very steady 1:45.09. But the 27-year-old knows he has plenty more in the tank.
"Between last year and this year there is a huge difference. I feel like I'm in better form now. Better, almost close to my body in the years 2010-2012. I've never felt as good as in previous years, since I got injured," he said.
ENNIS-HILL OVERSHADOWED BY COMPATRIOT
Reigning world and Olympic heptathlon champion Jessica Ennis-Hill was third following the afternoon session's two events.
Ennis-Hill's 12.84 seconds was the fastest in the 100m hurdles, but she was overtaken before the evening session by fellow Briton Katarina Johnson-Thompson and Belgium's Nafissatou Thiam.
The latter pair became involved in a thrilling high jump battle, both clearing 1.98m - a British record for Johnson-Thompson and a personal best for Thiam to move 22 and 10 points clear of Ennis-Hill respectively.
The evening session sees the heptathlon continue with the shot put and the 200m, while there are more medals up for grabs in the men's 20 kilometre race walk and the women's shot put.
On the track, the likes of Dafne Schippers and Kirani James begin their heats in the womens's 100m and men's 400m respectively.