Mo Farah will be seeking to establish his claim to be a world class marathon runner at this Sunday's race in London.
The 35-year-old World and Olympic champion at 5000 and 10 000 metres is switching to the longer distance with the Japan Olympics in mind. but knows that right now he's still off the pace of marathon specialists.
"I think I'm capable of running 2:04, 2:03 within the right race and the right pace but Sunday's race is going to be different, as you know." he said. "There's many, many guys to beat, to fight. So it's going to be a different race."
Twelve men in Sunday's race have recorded faster times than Farah, who has now returned to live in England and dropped controversial coach Alberto Salazar