Kenya's Eliud Kipchoge on Saturday made history, smashing the mythical two-hour barrier for the marathon in the "best moment" of his life on a specially prepared course in a vast Vienna park.
With a time of 1hr 59min 40.2sec, the Olympic champion became the first ever to run a marathon in under two hours in the Prater park with the course readied to make it as even as possible.
"I'm the happiest man today. The message that no human is limited is now in everybody's mind," an elated Kipchoge told reporters after the run, adding he expected more athletes to match his feat in the future.
"From the first kilometres I was really comfortable. I have been training for it for the last four and a half months, and above all I have been putting in my heart and in my mind that I'll run an under-two-hour marathon."
The 34-year-old already holds the world record for the distance with a time of 2hr 01min 39sec, which he set in the flat Berlin marathon on September 16, 2018.
But accompanied by a posse of 41 pacemakers, who took turns to support him, and a car in front of them setting the pace, Kipchoge bested his mark, making good on a failed attempt two years ago in Monza, Italy.
Maintaining a very regular pace at around 2:50 minutes per kilometre, he passed the finish line gesturing and smiling, describing his approach to the finish as "the best moment of my life".
The founder of the main sponsors, Ineos, British billionaire Jim Ratcliffe, took a personal interest in the challenge.
"That last kilometre where he actually accelerated was super human," said Ratcliffe, who himself competes in Ironman triathlons.
Kipchoge had been 11 seconds in advance at mid-race as fans lining the course, many waving Kenyan flags, loudly cheered him on.
Kipchoge's coach, Patrick Sang, said the Kenyan had "inspired all of us that we can stretch our limits in our lives".
Kipchoge told reporters earlier this week that his attempt in the Austrian capital was about "making history in this world, like the first man to go to the moon".
Because of the way the run was set up and paced the International Association of Athletics Federations will not validate the time as a world record.
The running surface had been partly retarred and readied with other features such as a banked corner that could save time and avoid injury.
Pacemakers took turns to support him throughout the 42.195-kilometre (26.219-miles) race. They included 1,500-metre Olympic champion Matthew Centrowitz and former world champion Bernard Lagat.
The course comprised a 4.3 kilometre-long straight alley, which the Kenyan ran up and down several times amid dry but foggy weather.
Throngs of fans cheered on Kipchoge whenever he passed by.
William Magachi, 33, from Nairobi, was one of many Kenyans watching in Vienna.
"It's amazing. He is a super human being, the positivity, what he has been able to achieve.
"It's a record breaking moment. It never happened and may never happen again in my lifetime... I'm a lucky man."
Another fan, Markus Parzer, 32 and from Vienna said: "It's absolutely amazing. I'm a runner as well, a hobby runner. Just running his pace for a few hundred metres, I can't do it longer.
"This really shows the magnitude of what he achieved today... It's really history made here in Vienna."
Fans from around the world also followed the run, broadcast live over YouTube and on many televison channels, as well as on a giant screen near Eldoret in west Kenya, where Kipchoge's family lives.
His number one fan, his mother Janet Rotich, was watching from her home.
"I am happy today because he has won... I thank him so much for this, for me, for Kenya and the world," she said.
"You've done it, you've made history and made Kenya proud while at it. Your win today, will inspire tens of future generations to dream big and to aspire for greatness," Kenyan president Uhuru Kenyatta said on Twitter.
Kipchoge already tried in May 2017 to break the two-hour barrier, running on the Monza National Autodrome racing circuit in Italy, failing narrowly in 2hr 00min 25sec.
The world marathon record has, for the past 16 years, been contested uniquely between athletes from Kenya and Ethiopia. The two nations are also fierce rivals for distance medals on the track.
Kipchoge's record was almost beaten last month in the Berlin marathon by Ethiopia's Kenenisa Bekele, who ran 2:01.41, just two seconds short of the official world mark.