It was that record performance in Monaco which made Kipyegon believe sub-four – once considered physiologically impossible for a woman – was within reach.
But the three-time Olympic 1500m champion still had a chasm to bridge, being required to run two seconds per lap faster than she had before.
Kipyegon was kitted out in an aerodynamic skinsuit and specially designed spikes as she targeted sub-60 second laps – an average speed of about 15 miles or 24 kilometres, per hour.
She was aided by 13 pacemakers, including Britain’s Olympic 1500m bronze medallist Georgia Hunter Bell and Jemma Reekie, as she chased the Wavelights tracking her progress on the inside curb of the track.
Kipyegon completed the third lap in 3:01.84, but her hopes of achieving the target gradually faded in the final 400m.
She still ran through the finish tape in the fastest time in history by a woman before collapsing to the ground.
The tape was held by her friend and training partner Eliud Kipchoge, who in 2019 became the first person to run a marathon in under two hours.
“I have proven that it is possible, it is only a matter of time. If it is not me, it will be somebody else,” Kipyegon said.
“I will not lose hope, I will still go for it. I hope I will get it one day.”
Sending a message to her daughter and young girls watching the record attempt, she said: “I will tell them we are not limited. We can limit ourselves with thoughts, but it is possible to try everything and prove to the world that we are strong. Keep pushing.”