Now, all the runners who did not automatically clinch spots in the semi-finals by placing race again in repechage round, with between two and six runners, depending on the distance, moving on.
The cheers for France's Anais Bourgoin in the 800 metres repechage on Saturday reached near ear-splitting levels with the new qualifying format in athletics proving popular at the Paris Olympics.
For the first time in Olympic athletics, runners who fail to advance out of the first round will be given a second shot through a repechage.
With the winner in each of the four women's 800 repechage heats sealing spots in the semi-finals, Bourgoin held on to win hers by about a 10th of a second, with the flag-waving crowd cheering as if she had won gold.
"Last night I could not sleep, but I had a nice massage and was trying to think about something else," Bourgoin said.
"When you are in your bed you are thinking about that adrenaline at the stadium and you cannot sleep. It was difficult to wake up at six (a.m.) but when you are very hungry for the win, you can do it.
"My feet hurt me a bit but when I heard the stadium I let (the pain) go and had to keep going. You have a lot of emotions when people scream your name."
World Athletics introduced repechage rounds -- which in French translates to "fish out" or "to rescue" and has been used in other sports such as rowing for years -- for Paris in the 100/110 hurdles, 200, 400, 400 hurdles, 800 and 1,500.
Races have historically included heats, semis and finals, with the "fastest losers" in qualifying -- runners who did not place high enough in their heats to advance but were among the fastest times of the non-qualifiers -- advancing to the semis.
Now, all the runners who did not automatically clinch spots in the semi-finals by placing race again in repechage round, with between two and six runners, depending on the distance, moving on.
The first round of the women's 800 was on Friday evening, making for a quick turnaround.
"It's certainly not easy, it really keeps you on your toes but it worked out for me because it got me through to the semi-finals," Australia's Abbey Caldwell said.
"At the end of the day it is going to make it harder and shorten that recovery but you've just got to take what you get."
