For two decades, Haile Gebrselassie enchanted fans of running with his mastery of the art.
Because he is such a rare athlete, because of his infectious joie de vivre and because he is an all-around admirable guy, it's now somewhat stressful to see him age. The wear and tear of a life that started on a poor, Ethiopian farm are making the double Olympic champion and four-time world champion in the 10,000 meters look increasingly mortal.
The world records in the marathon, 5,000 and 10,000 that once were his belong now to others. With his 39th birthday looming in April, Gebrselassie will never get them back. His ambition of competing at a fifth Olympic Games, in London this July, appears to be fading. His most recent marathon wasn't close to good enough to warrant a place on Ethiopia's Olympic team.
Which all begs the question: Should Gebrselassie retire? It's not that ''The Emperor'' of long-distance running suddenly has no clothes. But could he undermine his reputation by competing for much longer? Having done so much right over the years, is he getting the end of his career wrong? Is there such a thing as a messy retirement and, if so, can it tarnish the way in which an athlete is remembered?
The dilemma of how and when to stop isn't, of course, unique to Gebrselassie.
Lance Armstrong must have wrestled with it, too, when he U-turned on retirement and embarked on another two tours of France - in 2009, which turned out well, and 2010, which didn't.
Fans of American football grew familiar with aging Brett Favre's long summers of indecision before the sheer physical punishment of the game forced the star quarterback to retire.
At Manchester United, 38-year-old Ryan Giggs continues to poke Father Time in the eye on a regular basis. His match-winning goal last month in his 900th appearance for the English Premier League champion again showed how wise he's been to keep going.
But the argument that Michael Schumacher should have remained retired will gain traction if the seven-time Formula One champion fails again this season, the third of his comeback, to win a race.
Gebrselassie's manager, Jos Hermens, who first spotted the compact, fluid runner with a barrel chest at a cross-country race for juniors in Ethiopia in 1991, says there's no single, correct way for an athlete to retire.
Still, he wants Gebrselassie to finish his career with the same grace with which he runs. ''I don't want him to think in five years ... I should have stopped earlier,'' Hermens says.
After Sunday's Tokyo Marathon, Hermens suggested to Gebrselassie they should start planning his exit, perhaps with a farewell tour in 2013. Gebrselassie's fourth-place time of 2 hours, 8 minutes, 17 seconds, was more than three minutes slower than the sub-2:05s clocked by three Ethiopians at the Dubai Marathon in January. That means they, not him, are likely bound for London, because Ethiopia plans to send its fastest marathoners from 2012 - not necessarily its most famous - to the Olympics.
''Sunday night we had a conversation, and I suggested to him it's better to stop,'' Hermens said in a phone interview. ''I suggested to him to take 2013 as a sort of kind of year for goodbyes, like a pop star would do.''
But this is a tough one. Gebrselassie isn't short of other things to do. He builds offices and schools in Ethiopia. He has his family. He receives visitors. This week, British comedian Eddie Izzard, who ran 43 marathons in 7 weeks in 2009, trained with him in Addis Ababa.
But running has been Gebrselassie's life's goal since he borrowed his dad's radio as a 7-year-old to listen to a broadcast of distance runner Miruts Yifter win gold for Ethiopia at the Moscow Olympics in 1980. Running got Gebrselassie to school - 12 miles (19 kilometers) there and back every day - and all the fame and fortune he has accumulated since. It is easy to imagine that Gebrselassie might feel, as other athletes have done, that retirement is, in Hermens' words, ''the big black hole.''
''He's addicted to the schedule, getting up at 5 o'clock on the morning, training, in the office until 4 o'clock, then another training, and then go home in the evening,'' Hermens said. ''I didn't expect him to hold onto it. My feeling is that's also a little bad - holding on to something you really like.''
''He just wants to be the 21-year-old boy that could do everything he wants, with all his talents, to enjoy it, and go back to those days,'' he said. ''He's just in a transition stage of trying to accept, too, that he's not anymore one of the big boys. And we don't know, maybe in a few months he will realize, maybe it will take longer.''
Giggs adapted the way he plays football to compensate for his diminishing speed and endurance. Schumacher can cling to the idea that he'll win again just as soon as Mercedes gives him a faster car. But running is far less forgiving. The stopwatch brutally exposes those who no longer have the pace.
In the interview, Hermens talked in lukewarm terms of Gebrselassie possibly trying again at the Hamburg Marathon in April to qualify for London or maybe even aiming for one of Ethiopia's three spots in the Olympic 10,000. But he must earn it. There seems no question of Ethiopia gifting Gebrselassie a place, or of him accepting it, if he's not one of the fastest three.
''He doesn't like to be treated otherwise,'' Ethiopian Athletics Federation President Bisrat Gashawtena Tirfie said in a phone interview. ''He doesn't like any favors.''
Gebrselassie likes to say that age is only a mental thing. But is his body still willing? In Tokyo, he complained of back pain. He dropped out of the 2010 New York City Marathon with an inflamed, fluid-filled right knee and from the 2007 London Marathon with breathing difficulties.
Gebrselassie seems to be digesting that the London Games may now be beyond him, tweeting this week: ''It looks like my Olympic marathon dream is over.''
But Hermens is giving him time.
''He might go home and do track training next week and call me and say, 'Hey, I see possibilities,''' he said. ''There are still many options. Although, on the other hand, probably he will get injuries from the track and so then we'll get all the stupid excuses again - you know, problem lungs, problem back.''
''We all know at the moment he's a legend,'' he said. ''If he continues too long, then it takes away from his legacy.''
I, for one, disagree with that notion. Gebrselassie will be remembered for his achievements no matter how bumpily his career may end or how drawn-out it is.
Steve Cram, a former world champion and Olympic silver medalist in the 1,500 meters, agrees. Cram had a ''good few years'' toward the end of his career where he was injured, wasn't fit and didn't qualify for championships, ''but nobody comes up to me now and talks to me about that.''
''All athletes - myself, Seb Coe, Steve Ovett - we all had periods at the end of our careers when things didn't go well. We all had two or three championships where we weren't contending for medals and things and it hasn't damaged anybody's reputation as far as I can see,'' Cram said in a phone interview.
''In the long term, what people do is look back on the great things that you did in your career and Haile's got a whole list and he's right at the top of the list of distance runners. So I can't see that ever being taken away.''
John Leicester is an international sports columnist for The Associated Press. Write to him at jleicester(at)ap.org or follow him at twitter.com/johnleicester