Tens of thousands of people make their final preparations for this year's London Marathon, but only one person has the chance to win it for a record seventh time.
After winning four Paralympic gold medals at London 2012, David Weir decided against retiring. If he wins the marathon, he will exceed Baroness Tanni Grey-Thompson's six London victories.
The wheelchair racer from Sutton was unbeaten during last year's Games, winning gold in the 800m, 1500m, 5000m and the T54 Marathon.
Weir is to wear a black ribbon as a tribute to those who died in the Boston Marathon bombings on Monday, when he races tomorrow.
A 30 second silence at the start of the race will also take place.