JO Pavey described herself as 'mortified' after being forced to pull out of a marathon on Sunday.
The 39-year-old was taking part in the Yokohama women's marathon in Japan but was suffering from a sore throat and failed to last the distance.
Tiverton-based Pavey had been hoping to take advantage of the flat course and record a personal best time so was disappointed to have to withdraw during the race.
It is only the second time the Olympian has failed to finish a race in her senior career. The other time was when a calf injury forced her out of the 3,000m final of the European Indoor Championships in Madrid in 2005.
Pavey tweeted on Sunday: "Really disappointed. Perfect preparation and then had sore throat since Thursday night. Running can be so frustrating. Could not finish today."
She added: "Feel mortified. In nearly 30 years of racing that's only the second time I have stopped in a race. Last time was Euro Indoors when calf tore."
The race was won by Kenyan Lydia Cheromei in a course record 2hrs 23mins 7secs.
That was five minutes inside Pavey's best time, recorded on her marathon debut in London last year.
The Exeter Harrier was one of 18 runners up with the pace over the first 5k but she started to drift back with two other athletes around the 8k mark.
Cheromei broke away from the lead pack after 15k and won by more than three-and-a-half minutes.
Pavey is now taking some time off and will assess her plans for next year when she returns to the country after her holiday.