Double Olympic champion Mo Farah collapsed after crossing the finish line in the New York half-marathon on Sunday, having recovered from a fall earlier in the race to finish second to Kenyan Geoffrey Mutai.
Farah fell to the ground shortly after completing the race and was taken away from the finishing area in a wheelchair but later took to Twitter to allay fears for his health.
"Hi guys... I'm doing ok... thanks for the concern... disappointed with today... I gave 110%... couldn't do any more... sorry guys....," he said on his Twitter account.
The Briton, who won the same half-marathon in 2011, endured a tough run after taking a painful fall after five miles. He recovered to finish in 61 minutes 50 seconds - 18 seconds behind Mutai.
Farah, who won the 5,000m and 10,000m golds at the 2012 Olympics, is preparing to run his first full marathon in London in April.
Mutai's countryman Stephen Sambu finished third to round off a good day for Kenya in New York, with their compatriot Sally Kipyego winning the women's event.