36,500 runners expected at marathon
The wait is almost over for the fun runners, amateur athletes, celebrities and elite sportsmen and women taking part in the Virgin London Marathon.
Organisers estimate around 36,500 competitors will take their place on the start line in Greenwich on Sunday morning.
Forecasters are predicting dry and bright weather as the race gets under way, but warned there was a chance of rain later on.
Despite the attraction of Prince Harry presenting trophies to the winners, the serious runners will be using the race as a stepping stone to this summer's Olympics.
After Paula Radcliffe, Scott Overall, and Mara Yamauchi were named in Team GB's marathon squad in December, there are just two slots available for the men and one for the women. Overall will run as a pacemaker for the leading British men aiming for the Olympic A qualifying time of two hours and 12 minutes.
Lee Merrien, who was the first Briton across the line in last year's event, is one of the main contenders. Claire Hallissey and Louise Damen are among those battling for a place on the women's team. They have both already achieved the qualifying time of two hours 31 minutes.
In the men's race, Emmanuel Mutai will defend his title against five fellow Kenyans all vying for places on their country's Olympic team. Mutai smashed the course record to win in 2:04.40 last year, but will need to be at his best in a field which includes 11 men who have run under 2:06.
In the women's race, Mary Keitany will defend her title as she and her fellow Kenyans also look to secure Olympic selection, with the likes of world champion Edna Kiplagat, silver medallist Priscah Jeptoo and Berlin winner Florence Kiplagat all in the high-class field.
Forecasters are predicting temperatures will be about 8C (46.4F) as the runners set off, reaching 13C (55.4F) later with a "light to moderate" south-westerly wind.
Gareth Harvey, forecaster at MeteoGroup, the weather division of the Press Association, said: "It might be late morning or early afternoon by the time showers get going. If you're a quick runner you might miss them altogether. At the moment it looks like quite a nice start to the day, fairly bright and sunny but clouds building and a chance of showers later."