Ethiopian Kenenisa Bekele, the second fastest marathon runner in history, has withdrawn from this Sunday's London Marathon.
Bekele, who was due to race for the first time since he clocked two hours 01.41 minutes to win the 2019 Berlin Marathon, has a calf injury.
His withdrawal means there will be no showdown with Kenya's four-time winner and world-record holder Eliud Kipchoge.
Bekele said: "I am very disappointed that I cannot race on Sunday.
"It has been a tough preparation time with lockdown when I couldn't have my team around me. I was in good shape, but then I picked up a niggle in my left calf after two fast training sessions too close together in the last weeks of preparation.
"I have been having treatment every day since then and I truly believed I would be ready, but today it is worse and I now know I cannot race on it.
"This race was so important to me. My time in Berlin last year gave me great confidence and motivation and I was looking forward to show that again, I have worked so hard for it.
"I know many people around the world have been looking forward to this race and I am sorry to disappoint my fans, the organisers and my fellow competitors. I will take time to recover and become fit again and I hope to be back in London next year."
This year's race is restricted to elite athletes, with the usual 45,000 runners unable to take part due to the coronavirus pandemic, and will be run behind closed doors rather than along the traditional street route.
Britain's Jonny Mellor, who ran 2hrs 10.05mins in Seville in February, feels the new course – 19.7 laps around St James' Park – could be conducive to some quick times.
"It could be one of the fastest marathons you get to run," said the 33-year-old.
"There's no elevation on the course, it's nice and sheltered in the park, you can see other people ahead of you in the race. I'm looking at the positives.
"If you are having a good day it could be really good. But if it's a bad day it could be quite tough out there. It should be interesting, a bit of a novelty, and something to look forward to.
"We've done a little bit more on the track to prepare for it but at the end of the day it's still 26.2 miles. If I can get under 2:10 I'll be delighted."
Mellor already has the Olympic qualifying mark of 2:11.30 under his belt and fellow Brit Chris Thompson is desperate to join him.
"That's the aim and hopefully I can be in the mix," said Thompson, 39.
"Along with all the Brits everyone is looking for that Olympic standard. It feels like a free hit at it, because two or three months ago this opportunity wasn't there."
Sir Mo Farah will act as a pacemaker in the men's race.
