Reigning Olympic marathon champion Eliud Kipchoge fell just 25 seconds shy of becoming the first human to run the 26.2-mile distance in under two hours.
Kipchoge finished Nike's "Breaking 2" marathon on Saturday with a time of two hours and 24 seconds while running with a group attempting to crack the two-hour mark.
The 32-year-old Kenyan shaved eight minutes off his time at the 2016 Olympics to break the world record of 2:02:57 set by countryman Dennis Kimetto on at the 2014 Berlin Marathon.
Unfortunately for Kipchoge, his effort at Autodromo Nazionale Monza, will not count as an official world record because of pacing and hydration rules.
Kipchoge was joined by two-time Boston Marathon winner Lelisa Desisa and half marathon world record-holder Zersenay Tadese in the small group, which ran about 17 and a half laps of the 2.4-kilometre circuit.
"I hope next time, I can get it under the two-hour mark," Kipchoge said following his run.