Kenenisa Bekele, the three-time Olympic champion, four-time world 10,000 metres champion and 11-time World Cross Country champion, has committed to running his first competitive marathon later this year, so he is unsure what sort of speed he will have at his disposal around Arthur's Seat this afternoon.
Asbel Kiprop, the 2008 Olympic and twice world 1500 metre champion who was a winner at this BUPA Edinburgh International Cross Country meet two years ago, is in training mode - with the Commonwealth Games among his targets - so has no idea how well he will perform in the same race.
Steph Twell, the 2010 Commonwealth Games bronze medallist and the best known of the five Scots representing Great Britain & Ireland in the team races against Europe and the USA which follow the world-class 4km men's invitational race, has meanwhile been focusing on what she hopes will be a momentous track season. She, too, has little idea of what sort of form she will be in.
What is quite clear from their presence, however, is that the organisers of today's event have ensured that a year which will include perhaps the biggest athletics meet ever held in Scotland gets off to a magnificent start for the sport.
Furthermore, the variance in the readiness described by that trio merely reflects the uncertainty of cross country. On any given day, the overhead and underfoot conditions may better suit one or other of those competing in fields of this calibre, and those variables make for an element of risk, unpredictability and, consequently, added excitement.
Bekele's achievements, as well as a hat trick of wins in 8km races here between 2006 and 2008, entitle the Ethiopian to the No.1 shirt he will be sporting. He, admittedly, has unhappy memories of a shock finish outside the top 10 here two years ago - for the first time since he was a junior - but the 31-year-old offered a reminder of what he can do when he beat Mo Farah and his fabled countryman Haile Gebrselassie in last September's Great North Run.
He admitted, however, that a 4km cross country is a very different challenge to his planned step up to the marathon at Paris in the spring, while he faces today another modern great in Kiprop for whom this is an opportunity to further build relations with the country in which he plans to complete his medal haul later this year.
Until yesterday, it was not clear whether Kiprop - whose hale and hearty appearance ridiculed the claims that the Kenyan had suffered life threatening injuries in a car crash a few weeks ago - was aiming to compete in the Games, but he has now made a firm commitment.
Yesterday brought news that Jessica Ennis-Hill, the poster girl for the London Olympics, is definitely not going to take part, while there have been persistent rumblings that arguably the two biggest male stars in athletics, Usain Bolt and Mo Farah, will also withdraw. Kiprop's presence, then, would offer some solace for Games organisers.
"My coach has been telling me," he said, "that in my athletics profile I have the Olympic gold, I have two world championship golds, I have the All African Games and I have the African Championships, but there is no Commonwealth medal in my profile so he's been telling me it will not be complete unless I get a Commonwealth medal."
"If I am selected I will be at the Commonwealth Games."
Not that there is anything guaranteed about that, even with his record, as he pointed out in rather chastening terms when offering the hardly controversial view that Kenyan runners will dominate the middle-distance races at the Commonwealth Games and beyond. "Athletics has become a profession in Kenya and it is very competitive," said Kiprop. "Many athletes are coming up and the young ones are taking examples from others like those of us who have been champions and they would love to emulate us and follow in our footsteps.
"The trials are normally very tough compared even to the World Championships. I can remember in 2011 in my event, the 1500m, the winner ran 3min 31sec and at the World Championships it was won in 3.35 so you can see the difference."
Kiprop's own personal best is the fourth-fastest of all time, well below even that Kenyan trial time and for all that he is unsure of how he will run over 4km of hilly Edinburgh parkland in the cold he believes he could turn up in Glasgow next summer as a world record holder.
"Honestly I am trying this season to run 3.26 if not 3.25," he said. "That is my main goal."
His confidence in his ability to do so is boosted by the fact that, on the night double Olympic champion Mo Farah set a new British record in Monaco last year, the Briton had to settle for second place. He was a considerable distance behind the Kenyan who was setting that aforementioned best time of 3.27.72. "I wasn't prepared that night to run that fast that night. I could only imagine 'what if I did prepare, what if I took it on?' I could get something under 3.26," he said, adding that he believes his best chance to do so will be in Monaco, where there will be a Diamond League Meeting the week before the Commonwealth Games.
Right now, though, he claims not to know what he is likely to produce in competition, a sentiment echoed by Twell as she looked forward to the international match racing that will round off the day.
"I've not done as much cross country as I would normally do but I would like to have a positive run and be one of the points scorers for the team," she said.