It is going to be one of the most fascinating athletics stories of 2014, in fact one of the most fascinating sports stories. How will Great Britain's Mo Farah fare during his first full length marathon?
On Sunday April 13, all will be revealed when he makes his debut over the 26.2 miles in London.
He has the speed, he has the endurance, he has the ability to outflank and out think his rivals, but that is on the track. Now the double Olympic, triple world and triple European champion has to work out how to do all that on the changing surfaces of the road.
When Farah, 30, looks along the start line he will find himself in an unfamiliar position. Normally it is everyone staring at him as the best, now that scenario is in reverse.
The field announced for this year's London Marathon is as high-class as it could be, featuring Wilson Kipsang, the world record-holder, Olympic and world champion Stephen Kiprotich, defending London champion Tsegaye Kebede and course record-holder Emmanuel Mutai.
Farah could not be given a greater test and should he come through it and win, his stock as an athlete will go soaring even more.
“The London Marathon always attracts the world’s best runners to its elite fields and this year will be no different,' said Farah. 'I am expecting it to be one of my toughest races and a real learning experience.
“I had another great year on the track in 2013 but the marathon is my main focus for this year.
'As a young boy growing up in London it has always been my ambition to run the London Marathon and to be able to make my marathon debut in my home town is special.”
It is not his first time in the race. Twelve months ago he ran the first half to gain some tips for what lies ahead, learning some of the nuances of the course.
“I gained a lot of valuable experience alongside the top guys last year and can’t wait to race over the full distance this April,' he added.
On the track, Farah has become one of the all-time greats, a position he sealed by adding the 5000m and 10,000m at the IAAF World Championships in August to the same Olympic double from the previous summer.
At this year's European Athletics Championships in Zurich, he could chase a hat-trick of 5000m titles or maybe even the marathon?
With his slim build and economical running style - he has upright posture which is effective - Farah could be made for the 26.2 miles.
There was a great scene just past midnight after his Olympic 10,000m success when two hours after his race, he was back on the track doing lap after lap to warm down. Never mind what he had just put his body through to win gold, he was still pounding away.
Endurance should not be a problem - and like fellow Briton Paula Radcliffe, he could take to the marathon instantly and take the field apart. Let's not forget, he has such finishing speed that if he is in contention with a mile to go, there might be only one possible outcome.
Radcliffe did that in 2002 when she won on her debut in 2:18.56 and two years later on the same course took the world record to 2:15:25, a time which still stands.
Winning would be some outcome against such strong opposition which also includes one of his great track rivals, Ethiopian Ibrahim Jeilan, who beat him to 10,000m gold at the World Championships in Daegu in 2011 before Farah took revenge on him in Moscow.
London Marathon race director Hugh Brasher said: “Of course, much attention in Britain will focus on the performance of Mo Farah and we are very pleased that he has chosen London to make his marathon debut. But it will be an extremely tough challenge for Mo with the quality of the elite field as high as ever.'
We will follow his performance attentively since it could impact what distances he chooses to run for future major events.