"Haile has been having a problem with his left leg," said head national track coach Wolde-Meskel Kostre from Addis Ababa.
"He has been instructed by the doctor to do only light training. But we still have until a few days before the race to see how he is doing."
The 31-year-old Gebrselassie has dominated long-distance running for almost a decade, also winning four world 10,000 titles. But he was beaten at last year's world championships by young team mate and training partner Kenenisa Bekele and has since lost both his 5,000 and 10,000 world records to him.
Gebrselassie ran the fastest ever 5,000 metres on British soil at Crystal Palace the end of July but then flew to Germany for treatment on his injury.
Getanuh Tessema, who works with Gebrselassie's manager Jos Hermens, said on Sunday from Addis Ababa that the situation was being monitored daily. Asked if the runner could miss his event on Friday, he said: "That is a possibility.
"The injury has been causing him trouble. But that's Haile. He wants to fight till the very end."
If Gebrselassie were to drop out, he would be replaced by world cross-country silver medallist Gebre-egziabher Gebremariam.
Bekele, aged 22, is entered for both 5,000 and 10,000 metres in Athens.
