Haile Gebrselassie says he is in the best possible shape ahead of this Sunday's Flora London Marathon.
Gebrselassie is favourite to win Sunday's Flora London Marathon
"I've got very serious about it in the last seven months and I've trained for longer," said the Ethiopian, who set a new world record over 25km last month.
"We'll see on Sunday, but I think it will be pretty interesting."
Gebrselassie set a new national mark at last year's Amsterdam marathon, bad weather derailing what looked like a possible world record time.
"I think I may be in better shape than I was there," he said.
"It was not easy there, particularly the last part. The wind is just meant to affect the first part of the course, but it hit the last part more badly.
"I ran too fast in the first part, because I was told that the first part was the toughest. But it turned out to be the opposite.
"I have learned from that. And the good thing about London is that I know the course. I've run here before."
One of the greatest distance runners of all time, Gebrselassie did not find the step up to the marathon as easy as many were expecting him to.
A four-time world champion over 10,000m and twice an Olympic champion, he could finish only third on his marathon debut in London four years ago, albeit in the sixth fastest time in history.
"The marathon is not an easy thing," he admitted. "It's not like the 10,000m.
"It needs so much attention - it needs something very special.
"I thought the first time I jumped to marathons that it would be like training for the 10,000m, but it wasn't like that at all."
A calf injury to world record-holder Paul Tergat has robbed Gebrselassie of the chance to renew one of the great rivalries in distance running history.
The Ethiopian and the Kenyan met many times over 10,000m, with Haile always coming out on top, most memorably when he out-sprinted Tergat in the final few strides to take gold at the Sydney Olympics by just 0.09 seconds.
When they switched to marathons, the roles were reversed. Tergat beat Haile in London in 2002 and then took the world record with a brilliant performance in Berlin a year later.
Gebrselassie could be forgiven for secretly welcoming Tergat's late withdrawal - but he does not.
"I needed Paul in the race, not only because he is my competitor but because he is my friend," said Gebrselassie.
"When I see him run, I can learn a lot from him. When he ran the world record, I learnt from how he ran and how he prepared for it. I need him to get experience.
"People think that just because Paul isn't running that I just need to jump and I will win. But that's not true. This is running. This is sport."