Kenya's Eliud Kipchoge defended his Olympic marathon title on the final day of the Games.
The world record holder ran two hours 08.38 minutes to claim victory in Sapporo and become only the third athlete to retain their marathon crown.
The Netherlands’ Abdi Nageeye claimed silver as he finished one minute and 20 seconds behind Kipchoge, with Belgium’s Bashir Abdi third.
Ireland's Kevin Seaward crossed the line in 58th, 13.07 down on Kipchoge, with Holywood man Paul Pollock getting home in 71st place.
However, 29 of the field were forced to pull out in the hot conditions, including Stephen Scullion, who withdrew from the race around the 20km mark.
We need your consent to load this comcast-player contentWe use comcast-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
"It was really tough out there," the Belfast athlete admitted.
"I don't know that I want to be the guy that jogs off the start line and predicts that everyone's going to come back to him and fall off the pace.
"But maybe at an Olympic Games, where it's 30C and 85% humidity, that's what you have to do.
"It's almost a different sport. I guess it's not necessarily what most of the athletes here train for, but you should be willing to adapt and run to the conditions, and I obviously got that wrong today."
Reflecting on his run, Pollock said: "I got to halfway bang on pace and started trying to hunt through some people, but after about 2km everything just went pear-shaped and I went backwards.
"They always say in the marathon that it's emotional towards the end. I've never really felt that before, but I've got a two-year-old son at home and this is the longest that I've ever been away from him.
"That last 2km, my thoughts went to him because at that stage everything to do with the race was gone and it was just a matter of getting to the finish line."
Despite finishing best of the Irish, Seaward said: "It's probably the hardest marathon I've ever run.
"A lot of athletes went off conservatively. I tried to go through three to four minutes slower than my PB time through halfway, but it still bit later on in the race.
"I reset my goals around about halfway and then again in the last 5km. I went from 'move through and try to sneak into that top 40' to 'right, where's the finish line?'"
Kipchoge, 36, joined Ethiopia's Abebe Bikila (1960 and 1964) and East Germany's Waldemar Cierpinski (1976 and 1980) as the only runners to win back-to-back gold medals on the Olympic stage.
The world record holder has now won four Olympic medals overall, having also taken silver in 2008 and bronze in 2004 in the 5000m.
Kipchoge showed why he was the man to beat going into this race when he took full control as he pushed ahead of the pack after the 30km mark.
By the 35km stage he had jumped out to a lead of 27 seconds from a virtual tie 5km earlier and extended it to one minute and 17 seconds by 40km.
'I learned a lot about myself'— RTÉ Sport (@RTEsport) August 8, 2021
Marathon men Stephen Scullion, Paul Pollock and Kevin Seaward give their assessment of a gruelling morning#olympics #tokyo2020 #RTESport #athletics
📺 Watch live - https://t.co/IpdMKF55tD
📱 Updates – https://t.co/huAtW8EXqg pic.twitter.com/r4pPTKNb0N