Mo Farah has pulled out of Sunday's London Marathon due to a hip injury.
The four-time Olympic gold medallist, 39, suffered a problem to his right hip in training and will not be fit.
He said: "I've been training really hard over the past few months and I'd got myself back into good shape and was feeling pretty optimistic about being able to put in a good performance at the TCS London Marathon.
"However, over the past 10 days I've been feeling pain and tightness in my right hip. I've had extensive physio and treatment and done everything I can to be on the start line but it hasn't improved enough to compete on Sunday."
Farah was confident of a successful performance, having won warm-up race The Big Half in London earlier this month.
Event director Hugh Brasher added: "We are so sorry that Sir Mo is not fit to run on Sunday.
"We wish him a very speedy recovery and hope to see him running the 2023 TCS London Marathon in April next year."