HE says it was "great fun", but the marathon bruised his pride.
Now Mo Farah is back concentrating on what he does best, and does better than anybody else - the five and the ten. Not that he has banished the urge to explore his outer limits.
Track-and-field enthusiasts in Glasgow were already looking forward to the extraordinary privilege of watching the double Olympic and world champion race the 5000 and 10,000 metres at a customised, 44,000-seat athletics stadium - all for a relatively paltry outlay. Now there is an unexpected bonus: for our viewing pleasure, Farah will be putting on a much shorter and snappier show in 11 days' time, at the Sainsbury's Glasgow Grand Prix.
Given that the Somalia-born 31-year-old has already demonstrated a near-superhuman versatility by running the sixth-fastest 1500m time in history, the two-mile race he will headline at the Diamond League gala should be quite some spectacle, and Steve Ovett's 36-year-old world record may be living on borrowed time.
"It's just another race. I want to run tactically and run well but, at the same time, it would be good to win and get some confidence going into the Commonwealths," he said yesterday, talking on the phone from his training base in Portland, Oregon about the upcoming Grand Prix. "I haven't thought too much about [the world record] but Steve Ovett did it pretty well. We'll have a think as we get closer to it. Winning is more important."
That winning is important to Mo Farah has been underlined by his seamless switch in recent months from a position of apathy with regard to the Commonwealth Games to his current attitude, which can be summed up by the buzz phrase "bring it on".
The Diamond League is the kind of thing that allows athletes to retire with enough money to put their kids through college several times over, so they will always put their hand up for those one-off appearances. But the Commonwealth Games is a more complex proposition, as Farah explained carefully when asked about the Jamaican question.
Jamaica's approach to the multi-sporting extravaganza now just 22 days away remains a befuddling puzzle. Usain Bolt has, finally, confirmed that he wants to be part of it, while implying that he will only run an individual race if he is ordered to as a matter of national duty.
Yohan Blake, his nearest peer at the forefront of world sprinting, has stated that he will only be in Glasgow once this summer - and it will not be for the event that comes with the promise of a room in a fabricated village in Dennistoun and the right to party at the end. Ranking priorities are a conundrum for an elite athlete, but the fact that Glasgow is in the United Kingdom - for now, at least - is what swung it for Farah.
"It depends on the time of year," he said. "This year, many countries don't have big championships, like the USA. Jamaica's in the Commonwealth so it would be good to have Usain and Yohan and everyone there. But the world is a little bigger than anyone else. In my opinion, where you're planning years in advance, you're looking at the Olympics, the worlds and the Europeans [in that order], but with the Commonwealths it depends on where it is and where it fits in.
"It would be good to have Usain in the Commonwealths. It makes it exciting because he's a character.
"I haven't won the Commonwealth gold, so that would be nice to do as well, of course. But what really excites me is racing in Britain, the crowd always getting behind me," he added, recalling two nights in London that could never be knocked off top spot in his career highlights.
"If the Commonwealth Games were somewhere else, it would be different. I want to do the Commonwealths because they're at home, because they're in Glasgow. That should be exciting.
"The Olympics only come around every four years and to have it right on my doorstep, with the home crowd, 75,000 people cheering my name, that'll never be the same again. But, at the same time, when I race at home, I try to get similar support.
"Hopefully the crowd in Glasgow can carry me to the line - and that's what I'll definitely need. When it comes to athletics, we tend to come together as the UK. Even though I'm going to be competing for England, I think the Scottish people will still be behind me. I'm British and we get behind our athletes."
There will not be any trouble on that score on July 11-12 - and nor, we suspect, when Hampden opens its doors again to spiked shoes from July 26 to August 2. Scotland v England will not define the athletics competition as much as it does other sports. Besides, Farah is up there with Bolt, Hoy, Wiggins and the Brownlees as sporting demigods whose nationality is a secondary consideration to their global supremacy.
So now that he is not a marathon runner, with an eighth-place finish in London having dented his aura of invincibility, what celestial course will Farah chart next? Will he set his heart on world records in the five and ten?
"I don't know how close it would be to get to world records in the 5k and 10k," he said. "Realistically, the 10k might be closer but it all depends on what happens after the Commonwealths. You have to plan and see what's what."
For now, all that Mo Farah is thinking about is three races in Glasgow. It will be an extraordinary privilege to witness them.
n Watch 47 global medallists including Mo Farah, Yohan Blake, Christine Ohuruogu, Shelly-Ann Fraser-Pryce, Greg Rutherford and David Rudisha star at the Sainsbury's Glasgow Grand Prix as a part of the IAAF Diamond League series. For tickets please visit: britishathletics.org.uk