Kenyan Eliud Kipchoge set a new marathon world record in Berlin on Sunday, smashing the previous best as he clocked 2hr 1min 40sec.
The 33-year-old Olympic champion, aided by a string of pacemakers through to 25km of the 42.195km race, took 1min 17sec off the previous best set four years ago by Dennis Kimetto.
It was the largest single improvement on the marathon world record since Derek Clayton improved the mark by 2:23 in 1967.
"My only words are 'Thank you!'," said Kipchoge.
Acclaimed as the greatest marathon runner of the modern era, Kipchoge has dominated marathon racing since making his debut in Hamburg in 2013 after a successful track career that saw him win world gold and silver (2003, 2007) in the 5000m and Olympic silver and bronze (2008, 2004) over the same distance.
He has notched up 10 wins from the 11 marathons he has raced, winning three times not only in Berlin but also London, with victories in Rio for Olympic gold as well as in Hamburg, Rotterdam and Chicago.
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In the German capital on Sunday, Kipchoge had just a handful of pacemakers for company from the early stages of the race.
The Kenyan passed through five kilometres in 14:24 and 10 kilometres in 29:21.
But shortly after 15 kilometres, which was reached in 43:38, two of the three pacemakers were unable to continue and withdrew from the race.
The final pacemaker, Josphat Boit, led Kipchoge through the half-way point in 1:01:06 before dropping out at 25 kilometres, covered in 1:12:24.
Running alone with 17 kilometres left, Kipchoge then sped up.
He passed the 35-kilometre checkpoint just a shade outside 1:41:00, suggesting a finishing time inside 2:02 was possible. By 40 kilometres, reached in 1:55:32, a world record looked a certainty.
Kipchoge maintained his form well in the closing stages to smash compatriot Kimetto's previous best.
"Yes, it was tough running alone, but I was confident," he said.
"I'd said I was running my own course following my planning and I was confident." Kipchoge came agonisingly close to sporting immortality by nearly running the first sub two-hour marathon last year.
He missed the mythical mark by just 25 seconds.
But the race conditions at the Nike-sponsored event were so favourable -- Kipchoge ran behind a six-man pacesetting team and was trailed by a time-keeping vehicle on a racing circuit in Monza, Italy -- that the time was not recognised by the International Association of Athletics Federations (IAAF).