It was the morning after the night before and Mo Farah was as chirpy as the birds. Even the flit from photocalls to press conferences to sponsors' events was undertaken with the familiar geezer smile. But when Farah stopped to allow himself a moment of sweet reflection, he became serious. This latest win, 5,000m gold on Friday night, was "a lot harder", he admitted, than his previous four global titles.
"It was the hardest, as everyone knows what you're capable of," said Farah, who also had to defy a mid-race stitch, weary legs and gun-fresh opponents. "You can't hide. When you're at the top, it's easy to get knocked down. It might have looked easy but I had to dig deep. With 100m to go I could see [Isiah] Koech and I just had to dig in.
"I worked harder this year than last year," he added. "My split of 1.51 for the last 800m shows that. The guys who finished second and third could win any championships. They could have beaten me in London."
Farah's mentor and coach Alberto Salazar, the man who has taken him from perennial contender to undisputed champion in under three years, concurred. Except that he chose a different adjective. It was, said Salazar, Farah's "greatest single race".
"Running that last kilometre in 2.22 on dead legs compared to these other guys? That was amazing," he said. "I am lucky enough to see him train on a daily basis and Mo just continues to surprise me."
Salazar added: "His tactical brain is just incredible. I don't have to tell him stuff. I give him some ideas but going to the front and slowing it down – he's there for two laps and these guys don't figure it out! They're asking themselves, 'why is he going into the lead now?' He's like a magician."
Farah suggested that his glorious double-double at these world championships was helped by a rare slap of defeat – while weakened by a virus – from the Kenyan Edwin Soi in June, and a brutal training session that followed. "I killed myself after that," he said. "I was so angry and disappointed. I think that changed me. It was good to get beat. It made me train as hard as I could. We did a mile reps, six of them at around 4.05 pace, with a 600m jog for recovery. I remember just getting faster and faster, and at the end I was literally on my back."
In the giddy aftermath of Farah's latest victory, two questions were persistently lobbed in his direction. First, where did he stand among the greatest distance runners in history? And would fast times now follow championship victories?
On the first, Salazar is definite: he believes that Farah now belongs alongside the very elite, up there with Kenenisa Bekele and Haile Gebrselassie. "After the Olympics I was asked if I ranked Mo as the greatest distance runner ever but at the time there were several athletes who had done things he hasn't," he said. "But this win definitely puts Mo in the top three of all time."
Salazar believes Farah's move up to 26 miles is "exciting" and insists there are "no limits" to his potential – but he also warns that it will make world records on the track in 2014 almost impossible.
"I think he has a chance to go after track world records, but whether that can happen next year, I don't know," says Salazar. "Mo runs in London on April 20 and I believe it takes two months after a marathon before you can safely sprint all out. And I would be very hesitant to attempt in two months what we have done in four or five months this year."
Salazar, who as a former world record holder in the marathon is an emeritus professor on the strain the body undergoes at the distance, says Farah should postpone any track world record attempt until 2015.
"My advice to Mo would be: he's the best distance runner in the world right now, let's keep it that way and at a time that's right go for some records."
Farah seems to agree, saying: "Yes, it would be nice to run faster close to world records, but in my career medals mean much more to me than the world record."
Instead he is more focused on his next great challenge: the marathon. "I think it's having that belief," he says about his leap into the unknown in London.
"Many years ago I would have said you can't beat the Ethiopians and Kenyans. That's different now." And don't his opponents know it.