Sir Mo Farah will act as a pacemaker for the London Marathon after the elite field was revealed.
The race will only involve elite athletes, with the usual 45,000 runners unable to take part because of the coronavirus pandemic.
Eliud Kipchoge and Kenenisa Bekele headline the race, which will be held on a bio-secure closed course on October 4.
World Athletics will lift its suspension of the Olympic qualification system for marathon races from September 1, meaning athletes have the chance to achieve the Olympic standard of two hours 11:30 minutes.
Farah, who came third in the race in 2018, said: "The London Marathon has been so important to me since I was a schoolboy and when they asked me to do this I thought it would be great to help.
"I am in good shape, I'll be in London that week and it fits in with my training.
"I've been training in Font Romeu with some of the British guys who are going for that Olympic qualifying time and they are good lads.
"I know just how special it is just to compete for your country at an Olympic Games and it would be great to help other athletes achieve this.
"With the current global situation and lack of races, the Virgin Money London Marathon in October is the best chance for athletes to run the Olympic qualifying time."
Farah will return to the track to defend his 10,000m title at next year's delayed Olympics while Callum Hawkins has already been pre-selected for Team GB.
Steph Twell, who ran a personal best of 2:26:40 in Frankfurt last year to go sixth on the British all-time rankings, will compete in the women's race.
The route will be around St James's Park in central London with the finish on The Mall remaining the same as in previous years.
It is the 40th anniversary of the race and the first time it has been elite athletes only.
