He doesn't think it's possible, at least at the moment.
Rhonda Copeland started losing her vision in the 1990s.
He thinks he can pull it off.
She has already proven herself on the track and roads in shorter distances.
They have unique goals at Sunday's race.
He will run his first marathon on Sunday.
Over 30% of runners will be debuting.
A record 25,000 entrants took part in the race's 11th edition.
He is doing it to raise money for two charities.