Mo Farah began his track finale after a thrilling defence of his 10,000 metres title at the World Championships, while Usain Bolt was unhappy with his performance in the 100m heats.
With 55,000 of his home fans roaring their support at the London Stadium, the 34-year-old Briton sprinted away with his 10th consecutive gold medal in a global track final.
Farah survived being clipped twice from behind in the final lap, nearly tripping over, before unleashing a trademark burst down the home straight to burst away from Ugandan silver medallist Joshua Cheptegei and Kenyan bronze medal winner Paul Tanui.
The Briton clocked 26 minutes 49.51 seconds, the world's fastest time in 2017, in what proved perhaps the hardest-earned of all his magnificent triumphs as he protected his six-year unbeaten streak in major championships.
"It was amazing. I had to get my head around it and I got a bit emotional at the start. I had to get in the zone."
Cheptegei clocked a lifetime best 26:49.94 and Tanui 26:50.60 but, five years to the very night when he won the 25-lap title at his home Olympics on "Super Saturday" in the same London Stadium, Farah had still not lost that invincible aura.
It was the perfect way for Farah to begin his final championship as a track runner before he turns his attentions to the roads as a marathon man.
"What a way to end my career in London. It's special," Farah said, after hugging his children on the track.
"It was amazing. I had to get my head around it and I got a bit emotional at the start. I had to get in the zone.
"It wasn't an easy race. I work on everything and it's been a long journey."
After an epic test in which the powerful Kenyan and Ugandan athletes combined with mid-race bursts to test Farah's resolve more fiercely than ever before, the Briton had to show remarkable composure on the final lap.
Twice as he led straight after the bell, Farah was caught as his pursuers jostled to take pole position. The first one saw his heel clipped and on the second occasion just on the second bend, Tanui seemed to flick his arm, sending Farah off balance.
Yet despite momentarily losing his rhythm, the champion regrouped to take control on the back straight and he scorched off the final bend to forge clear and take his third successive world 10,000m title by a couple of metres.
Usain Bolt was left furious with his performance, despite moving a step closer to a golden goodbye as he cruised through the 100 metres heats at the World Championships in London.
Back at the stadium where the Jamaican declared himself a "living legend" after retaining his 100m and 200m titles at the 2012 Olympics, the 30-year-old had to recover from an awful start to win his heat in 10.07 seconds.
Bolt, who is bringing the curtain down on his glittering career at these championships, was met with the customary huge cheers whenever he appeared on the big screen.
He whispered "number one" when the camera panned to him on the start line, but the shake of the head at the finish was proof he was less than happy with his run.
"I stumbled coming out of the blocks."
Bolt's start has been his chief - perhaps only - problem throughout his career, no great surprise for a sprinter who stands 6ft 5in.
"That was very bad," Bolt said.
"I stumbled coming out of the blocks. I'm not very fond of these blocks. I think these are the worst ones I've ever experienced. I have to get this start together because I can't keep doing this.
"It's shaky. When I did my warm-up it (the blocks) pushed back. It is just not what I am used to, not as sturdy or firm.
The individual career of the world's greatest ever sprinter, and by common consensus the world's greatest ever athlete and track and field's entertainer-in-chief, has just one more day to run.
On Saturday he will look to pocket a 12th world title, to go with his eight Olympic crowns and an underwhelming farewell is almost unthinkable.
