London Marathon: Gebrselassie asked to set world record pace
Former world record holder and two-time Olympic 10,000m champion Haile Gebrselassie will be lead pacemaker at this year's London Marathon.
The Ethiopian, 40, clocked two hours, three minutes and 59 seconds in 2008 and will attempt to take the field to the 30km mark at world record pace.
"I'm going to do something useful to keep the right pace at the right time to attack the world record," he said.
Great Britain's Mo Farah will form part of a stellar men's field on 13 April.
Farah, who ran half of last year's race as a training exercise, will make his debut over the full 26.2-mile distance this year.
The double Olympic champion will face current world record holder Wilson Kipsang and Stephen Kiprotich, who holds both the world and Olympic marathon titles.
Gebrselassie has broken 27 world records and claimed victory in four Berlin Marathons - a race where the world's top athletes often target the world record.
London race director Hugh Brasher said: "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."
Last year's London Marathon winner Tsegaye Kebede of Ethiopia will also compete, as Farah, 30, attempts to become the first Briton to win the race since Eamonn Martin in 1993.
"In his first marathon, [Farah] doesn't need to win or run a fast time, but learn about the distance," added Gebrselassie, who moved up to marathon distance from track at 29.
"He can do what he wants in his second or third marathon. I only ran 2:06 in my first one and after that I returned to the track as it was too early.
"In terms of his speed, Mo can run more on the track. He ran three minutes 28 seconds for 1500m, which I couldn't do. To do a marathon is up to him, he can run a good one."