Haile Gebrselassie says he will not run in the marathon at the 2008 Beijing Olympics because of the city's air pollution levels.
Gebrselassie has set 26 world records during his career
The marathon world record holder suffers from asthma and missed the 2007 London Marathon because of the problem.
The 34-year-old will now try to qualify for Ethiopia in the 10,000m at Beijing.
"The pollution in China is a threat to my health and it would be difficult for me to run 42km in my current condition," Gebrselassie told Reuters.
"But I'm not pulling out of the Olympic event in Beijing all together. I plan to participate in the 10,000m event."
But Gebrselassie's agent said the Ethiopian will make a final decision on whether to run the Beijing marathon after the Hengelo meeting on 24 May in Holland, when he will know if he has qualified for the Olympics 10,000m.
"Haile wants to do everything possible for his country," agent Jos Hermens told the Associated Press. "With three Ethiopians, they could get gold, silver and bronze.
"And if you look deep into his heart, he wants another marathon record."
The International Olympic Committee has voiced concerns over the issue of air pollution in Beijing.
If contingency measures do not have the desired affect then endurance events could be delayed for a few hours or rescheduled for another day.
Last year Britain's Paula Radcliffe called in pollution experts to help her plans to run in the Games marathon.
At the time her husband and manager Gary Lough told BBC Sport that Radcliffe, who suffers from exercise-induced asthma, may have to change her medication in China.
"She may have to adapt her doses or medication but as long as we've done enough research and thought about it, it hopefully won't be an issue," he said.
"There's no point in us being especially concerned, because pollution's not really something you can control."