The British athlete, Mo Farah, has become the first man to win back-to-back world distance doubles after storming to victory in the 5,000 metres at the World Championships in Beijing.
The Briton, rocked this season by doping allegations against his coach, put the row behind him as he produced a devastating final 80 metres to romp home in 13min 50.38 seconds.
Kenyan Caleb Ndiku, in 13: 51.75, held on for silver after making a valiant break with 800m to run. Ethiopian Hagos Gebrhiwet took bronze.
The victory for Farah, who won the 10,000 metres on the opening weekend, seals a unique "triple double" of distance titles at consecutive world championships and the London Olympics.
"Tonight I had to dig deep, it came down to the last 100 metres," said the Somali-born Farah, 32. "I felt a bit tired going through the rounds and coming back again.
Farah's victory gave him an unprecedented seventh successive distance win at world championships and Olympics, stretching back to his 5,000m gold at Daegu in 2011.
The American Ashton Eaton retained the decathlon world title in the Bird's Nest Stadium on Saturday, breaking his own world record by scoring 9,045 points.
After just five hours sleep, however, the 27-year-old admitted he had doubts over whether he could break the record.
In the 10th and last discipline, the 1,500 metres, he needed the help of one of his rivals to drag him around the final lap in a fast enough time.
Competing in his first decathlon for two years, Eaton had to run four minutes 18.25 seconds to score the 824 points required to break the world record.
"I knew with 300 metres to go that I was behind, and I said, 'Oh crap! I better go'," Eaton told reporters.
"I could see the Algerian Larbi (Bouraada) in front of me and I used him. I could tell, he sped up. I caught up again and he sped up again. So I thank him for that."
Eaton stopped the clock at 4:17.52 to score 829 points and break his old mark, set in 2012, by six points.
The silver medal went to Canada's Damian Warner with a national record 8,695 points and Rico Freimuth of Germany took bronze with 8,561.
There had been little doubt through the second day that Eaton would win gold and it was all about whether he could better the record.
The Olympic gold medallist had run 45.00 seconds in the 400 metres on Friday, the fastest ever by a decathlete during a multi-event.
With one day of the meeting to go, Eaton's is the only world record to be broken at the Beijing championships.
Eaton is married to Canadian heptathlete Brianne Theisen- Eaton, who won the world silver medal here earlier this week.
Marina Arzamasova of Belarus outsprinted defending champion Eunice Sum down the home straight to win gold in the women's 800 metres.
The European champion kicked for home off the back straight and found enough gas to hold off her Kenyan rival when Sum attacked after the final bend, claiming her first major title in one minute 58.03 seconds.
"I dreamed about the gold medal at world championships all my life and now I have this medal," the 27-year-old told reporters.
"It was a good race, not so fast, and I was ready from the beginning to the finish. I knew all girls can finish strong, so I decided to start it on the last 200m.
"I think from tomorrow on I will start preparing for the Olympic Games in Rio."
Canada's Melissa Bishop stayed with the leading pair on the last 100 metres and got just in front of Sum at the line to claim silver in 1.58.12.
Piotr Malachowski of Poland claimed the discus gold medal with a throw of 67.40 metres.
The 32-year-old Pole dominated the event to finally win the world title after landing silver medals in 2009 and 2013 and being Olympic runner-up in the same Stadium seven years ago.
Malachowski thanked his compatriot and women's hammer world champion Anita Wlodarczyk for her contribution to his victory.
"Anita came to my home and told me just one piece of advice," Malachowski told reporters. "She said: 'Throw far'."
The silver went to Philip Milanov, who broke the Belgian national record with 66.90 metres, and Malachowski's Polish team mate Robert Urbanek took bronze with 65.18.