A 100m race was scheduled for day two of the Rio Olympics athletics competition but Mo Farah decided to hold one of his own in the 10,000m final.
Locked in a titanic battle with Kenyan Paul Tanui, Farah outsprinted his opponent down the straight to retain his title and become Britain's first three-time Olympic track champion.
Both men had reached the 9,900m mark in a time of 26min 51.8sec, leaving the gold medal to be decided by less than half a second.
Farah clocked 13.37sec over the last 100m to finish in 27:05.17 - just shy of the Ethiopian great Kenenisa Bekele's Games record of 27:01.17.
Tanui took silver with 27:05.64, while Ethiopia's Tamirat Tola was third on 27:06.26.
With the 5,000m still on his plate, Farah had no intention of divulging where that famous speed and closing kick comes from.
"I've been running (since) I was 12, I've learnt what (the) body can and cannot do," said Farah, 33, who shaves his head before each race.
"I'm not going to give away my secrets, but I work hard in training and if you work hard at something you can achieve it. Each year when you win something you get more confident."
Farah is the foremost middle-distance runner of his generation. This was his eighth consecutive win in the 5,000m or 10,000m at a world championships or Olympics since 2011, when he last lost the 10,000m to Ethiopian Ibrahim Jeilan at the Daegu World Championships.
Farah's 5,000m-10,000m double in London ranked him with Emil Zatopek of Czechoslovakia and Bekele, whose feats came in 1952 Helsinki and 2008 Beijing respectively. The Somalia-born runner said: "It feels amazing to be part of history along with those guys... It's nice to be recognised as one of the best in the world."
Should Farah win the 5,000m on Wednesday, his legacy will be even greater. Finland's Lasse Viren is the only man to complete the double twice (1972-1976). In an eerie link to Viren, who fell during the 10,000m at the 1972 Munich Games but still went on to win, the same thing happened to Farah in Rio.
Training partner Galen Rupp (fifth, 27:08.92) clipped his heel during his 10th lap to send Farah tumbling but he quickly recovered.
Unlike four years ago when Team GB celebrated "Super Saturday" with victories for Farah, long jumper Greg Rutherford and heptathlete Jessica Ennis, only Farah managed to keep his title this time. Rutherford was third, with Ennis second.
It made Farah's victory lap all the more poignant on a evening where Jamaican Shelly-Ann Fraser-Pryce's bid for a historic sprint hat-trick fell short.
In the real 100m race, the two-time Olympic champion was beaten by compatriot Elaine Thompson, who clocked 10.71sec, ahead of United States' Tori Bowie (10.83) and Fraser-Pryce (10.86).
Thompson, eyes wide open, looked stunned as she crossed the line. She had won the biggest sprint of her life. An hour earlier, Farah had already triumphed in his.