Count Alucard wrote...
Also,the 4th hokage (strongest hokage in history) couldn't beat Madara so why would he be scared of the 1st?
He wasn't really the strongest... He was the greatest hero in Konoha's history.
Also, When fighting the nine-tails, he found out who
was controlling the nine-tails. Then he sealed half of it's chakra inside Naruto knowing it will be very useful in the future.