
The marathon world record holder, who won Olympic gold in the 10 000m in Atlanta and Sydney, made his decision after limping out of his first New York Marathon with a knee injury.
Coe, who won the Olympic 1 500m title at the 1980 Moscow Olympics and successfully defended it four years later at Atlanta said: "We will wait a long time before an athlete dominates over so many distances and across such an extraordinary time period as Haile Gebrselassie has done.
"The litmus test for a successful athlete is longevity at the very highest level and he had that in abundance.
"There is nothing he couldn't do - and he did it with style. I believe he is the greatest athlete of the last 50 years and arguably the best of all time."