Eliud Kipchoge missed out on becoming the first athlete to run under two hours for the marathon by 26 seconds.
The Kenyan, 32, clocked 2:00.25 but due to the use of in-out pacemakers, the time will not be recognised as a world record, meaning Dennis Kimetto's mark of 2:02.57 is still the quickest.
But Kipchoge said: "This is history."
Eritrea's Zersenay Tadese and Lelisa Desisa of Ethiopia also raced in the behind-closed-doors Nike event in Italy but faded earlier in the attempt.
The three athletes chased the landmark time running 2.4km laps on the Monza Grand Prix circuit, 63-years to the day since Britain's Roger Bannister ran the first ever sub four-minute mile.
Monza was chosen by the sportswear company for its gentle corners and favourable climatic conditions, while pacemakers were instructed to shield the trio from the wind and drinks were delivered to runners on scooters to save them from slowing down in collecting bottles.
'Truly inspiring' - Radcliffe
Kipchoge ran each mile at an average pace of around four minutes and 36 seconds. To achieve a sub-two clocking, the Olympic champion would have effectively had to run 17 seconds for 100 metres 422 times in a row.
He lapped 26-year-old Desisa, who finished in 2:14.10, while Tadese, 35, came home in 2:06.51. Kipchoge always looked the stronger and was on target pace with around seven miles to go but he began grimacing in the closing stages and though he tried to sprint up the home straight, his fatigue was obvious.
Pacemakers applauded and encouraged him as he approached the line and the clocking comfortably outstrips his recognised personal best of 2:03.05, set at the London Marathon in 2016.
"I'm happy to have run two hours for the marathon," added Kipchoge. "My mind was fully on the two hours but the last kilometre was behind the schedule. This journey has been good - it has been seven months of dedication."
Women's world-record holder Paula Radcliffe called Kipchoge's run "truly inspiring".
Only a select few media were allowed in to witness the attempt at the race circuit near Milan.
Nike paid the three runners to forego the London and Berlin Marathons this year prompting some criticism of the event given the resources invested and the fact it will not count as a legitimate record.
Nike's big corporate rival, Adidas, is planning its own sub two-hour marathon attempt but wants to do so in a race setting.