Mo Farah blitzed to a new world record in the rarely-run one-hour event on his return to the track on Friday at an empty Brussels stadium that also saw Sifan Hassan set a new best in the women's equivalent race.
Three years after having opted for road running, Farah showed no sign of cobwebs as he ran 21.330 kilometres over the 60 minutes behind closed doors at the Brussels Diamond League meet at the King Baudouin Stadium.
Farah, who won 5,000-10,000m doubles for Britain at both the London and Rio Olympics, bettered Ethiopian Haile Gebrselassie's previous best of 21.285km, set back in 2007, by 45 metres.
"I'm very pleased to break the world record today," said Farah. "What an amazing way to do it and show people what is possible."
It was a formidable record: the equivalent of 52-and-a-half laps at an average of 67 seconds per lap, or 2:47min per kilometre.
And at one stage, the 37-year-old Briton, also a six-time world gold medallist, looked to have dropped that vital programmed pace, with Belgian training partner Bashir Abdi still in the running.
There might have been no crowd thanks to coronavirus-induced health protocols, but the record attempt featured piped-in music, audience cheering and a visual time guidance aid: 400 LED lights installed in drainage covers that lit up to mirror the desired pace.
Farah and Abdi duly took note of the flashing lights and upped the pace to get back on record-setting time.
With five minutes to run, Abdi took the lead for the first time, sweeping Farah around on his coattails.
As the gun fired for the final minute, Farah opened up his rangy stride to shoot past the Belgian and maintain his form through to a second gunshot that ended the race.
While Farah holds every British record for all events between the 1,500m and marathon, it was his first ever world record.
- Concentrated Hassan -
Ethiopian-born Dutch runner Hassan, like Farah once a member of the now-disbanded Nike-backed group of disgraced coach Alberto Salazar, smashed the women's world record.
Hassan, the reigning world 1,500 and 10,000m champion, produced a thrilling kick over the final minute to see off Kenya's world marathon record holder Brigid Kosgei (who was later disqualified) and notch up 18.930km.
Hassan's final distance added 413m -- more than a lap -- to the previous record of 18.517km set by Ethiopian Dire Tune Arissi in 2008.
"I'm very happy," said Hassan, who last season also set world record marks for the mile (4:12.33) and 5km on the road (14:44).
"An hour is long, it takes a lot of concentration and focus. After the first half I found my rhythm. I never thought I'd run so far!"
There was no such luck for Faith Kipyegon, however, the Kenyan once again thwarted in her attempt to break the long-standing world record in the women's 1,000m.
The reigning Olympic 1500m gold medallist missed out on bettering Russian Svetlana Masterkova's WR of 2:28.98 set back in 1996 by just 0.17sec in Monaco.
This time out, Kipyegon paid the price for a slight lapse in tempo halfway through the race, finally coming through in 2:29.92.
Norway's Jakob Ingebrigtsen, who claimed the European 1,500m record from Farah when he finished second in Monaco to Timothy Cheruyiot last month, blitzed to victory in the event in the Belgian capital, in 3:30.69.
In his last race as a teenager, the 19-year-old was paced through to the line for a facile victory, two seconds off his continental record.
"That was really fun, finally I could take a win!" joked the Norwegian.
"In the final metres I missed someone to push me. It's impossible to run a really really fast time if you're all on your own."
World heptathlon champion Katarina Johnson-Thompson bagged a season's best of 13.57sec as she finished fourth in the 100m hurdles won by local Anne Zagre (13.21), before high jumping a best of 1.84m for sixth in an event claimed by Australia Nicola McDermott (1.91).
Sweden's Armand Duplantis, fresh from a world lead and new outdoor personal best of 6.07m in Lausanne this week, won the men's pole vault with a best of 6.00m, a meeting record.