Sir Mo Farah is not competing at the Tokyo Olympic Games after failing to qualify.
Farah missed his final attempt to qualify for the 10,000m event at the British Athletics Championships last month in a crushing blow.
He needed to go under 27 minutes 28 seconds at Manchester Regional Arena to book his place on the plane to Tokyo but could only manage 27 minutes 47 seconds and was therefore not able to defend the 10,000m title he won in 2012 and 2016.
He could now walk away from the sport.
He said: “It’s a tough one. I’ve always said if I can’t compete with the best I won’t just go to be in a final. Tonight showed it’s not good enough.
“You go out there and give it all and that’s all you have. I tried to push and push and I ran my lungs out.
“That’s all you can do as a human being, give it your all. I’ve had a wonderful career. I’m very grateful."
Farah was targeting history in Japan with no Olympian ever winning five gold medals over 5,000m and 10,000m.
Earlier this month he revealed he had a fractured left foot and had been struggling "for a while".
"You know what goes up must come down at some point," he told the BBC's Victoria Derbyshire.
"But at the same time I don't want to end it like this. I want to continue to keep pushing and feel like when I want to finish, then I'll finish.
"Right now, at the minute, it's like nah.
"I want to celebrate at the end with my fans and want to show people who have been supportive throughout my career from a young child.
"If I do one race I'll get everyone out and show the appreciation and see what I can do."
During an illustrious career he won Olympic 5,000m and 10,000m doubles in both 2012 and 2016.
Although he was not able to qualify to defend his titles in Tokyo this summer, Farah can boast a haul of four Olympic gold medals, six World Championship titles, five at the Europeans, as well as two World Championship silver medals. He was named BBC Sports Personality of the Year for 2017.
Away from athletics, he appeared on last year's edition of I'm a Celebrity... Get Me Out of Here, which was filmed in Wales.
