Mo Farah admits he will face a daunting challenge when he makes his marathon debut in London on April 13.

The double Olympic and world champion over 5000 and 10,000 metres will take on the world-record holder Wilson Kipsang, the Olympic and world champion Stephen Kiprotich, reigning champion Tsegaye Kebede and course record holder Emmanuel Mutai will all be in the field for the April 13 race.

The size of the task means victory, should he pull it off, would be arguably his greatest achievement yet, eclipsing his London 2012 and World Championship achievements. Kenenisa Bekele is the only notable absentee, with the Ethiopian great, who beat Farah in a thrilling half-marathon race at the Great North Run in September, due to make his marathon debut in Paris on April 6 instead.

Farah ran half the London course during last year's race to gain experience and claiming at the time he had "learned the biggest lesson of my life", saying he had no problem with the pace but getting the drink stops right had been a challenge.

"I gained a lot of valuable experience running part of the course last year and can't wait to race over the full distance this April," he said on Monday. "London always attracts the world's best runners to its elite fields and this year will be no different. I am expecting it to be one of my toughest races and a real learning experience. I had another great year on the track in 2013, but the marathon is my main focus for this year."