Jeptoo faces tough challenge to keep her London crown LONDON (Reuters) - Kenyan Priscah Jeptoo will face a strong challenge for her London Marathon crown as the Olympic champion, the world champion and one of the greatest distance runners of all time line up against her on April 13. Olympic champion Tiki Gelana of Ethiopia, world champion Edna Kiplagat of Kenya and double 10,000m Olympic champion Tirunesh Dibaba of Ethiopia are the front runners in a field that includes eight athletes who have run under 2 hours 25 minutes. The world record stands at 2:15:25 and was set by Britain's Paula Radcliffe in London 11 years ago. London Marathon race director Hugh Brasher, announcing the field on Wednesday, said: "We are delighted to welcome back Priscah Jeptoo. Our champion was a deserved winner of the World Marathon Majors title and has shown with her performances over the last two years that she will be extremely difficult to beat. Jeptoo, who won an Olympic silver in London in 2012, produced the world's second fastest time last year to win in 2:20.15 and she will need to reproduce that kind of form against an elite field that also includes three athletes who have run quicker than 2 hours 20 minutes. Jeptoo followed up her London win with victory in the New York Marathon in November when she clinched the World Marathon Majors title and a $US500,000 pay cheque. Dibaba, who has won three world 10,000m titles, two world 5,000 meters crowns and three Olympic titles, will be making her debut over 26.2 miles (42.195kms). Among the eight athletes who have run under 2:25, three have run under 2:20: Gelana, whose personal best is 2:18:58, Kenyan Florence Kiplagat (2:19:44) and her namesake Edna Kiplagat Reporting by Mike Collett; editing by Martyn Herman