The 5,000 and 10,000 metres champion at London 2012 will run his first marathon in the British capital in April.

"My worry for Mo is that he's very good on the track...he can run faster on the track than in a marathon," said Gebrselassie, who will run as pacemaker at the Virgin Money London Marathon.

"Mo's 31 [in March], it's the perfect age for a marathon.

"But if he thinks to stay on the track, that would be the best [thing]."

Farah ran half of last year's London Marathon in preparation for running the full distance this year.

He will face an extremely strong field, with world record holder Wilson Kipsang, reigning London Marathon champion Tsegaye Kebede, world and Olympic marathon champion Stephen Kiprotich, and London Marathon course record holder Emmanuel Mutai all set to line up in April.

Mo Farah followed up his double Olympic gold in London with double gold at the Athletics World Championships in Moscow last year, but has now turned his attentions to marathon running ©Getty Images



Gebrselassie, who won 10,000m gold in the Atlanta 1996 and Sydney 2000 Olympics, added: "I don't want to expect a lot from Mo. If he wins it will be so special.

"In your first marathon, to run a good time, that's the best.

"If he's fourth or fifth, I don't see it as a disaster, I see it as a success – no question about that."

Ethiopian Gebrselassie pointed to Farah's blistering 1,500m pace as evidence of what he can go on to achieve on the track if he focuses on it.

"Me and Kenenisa [Bekele] didn't run 3 mins 28sec, but he did. He's got a chance to break old records in the 10,000m or the 5,000m."

It is the first time Gebrselassie will have run as a pacemaker at a marathon - leading the field of elite runners to 30km (18 miles) at world record pace.

"Everyone knows how difficult it is to break the world record on London's course, especially with such a competitive field, but with Haile pacing and four of the fastest marathon runners in history in the race, there's a real chance we will see something special," said London Marathon race director Hugh Brasher.

Gebrselassie ran the London Marathon three times as a competitor.

He was third on his marathon debut in 2002 and ninth in 2006.

He was forced to drop out in 2007 when he had problems with asthma, but says the shorter distance he is running this year means it will not be an issue again.