Ethipian's Etenesh Diro fought to qualify for the 3,000m steeplechase semi-finals, despite losing a shoe part way through the race.
There were still two and a half laps to go when her right shoe came off after she got tangled up with two other runners. She tried to put it back on but decided it was taking too long, so she tossed it aside.
After a couple of steps Diro pulled her sock off and threw that to one side too.
She received the biggest roar the stadium has heard so far as she battled back through the field. Her seventh-placed finish in 9:34.70 was not enough to go through, but she advanced to Monday's final after lodging an appeal.
Diro had to be helped off the track by the medical team at the end of the race.
Needless to say, it was pretty inspiring.