Who was the power behind Octavian Caesar?

How is it possible that an 18 year old boy who never was in a real battle, went up against all the heavyweights of Rome.My question is: was there a power behind Octavian that we do not know about or have not been told about.For example how is it possible that this young sickly boy could out maneuver Mark anthony who was a battle hardened solder. What about Cicero or any of the other heavy weights in Rome. Its just not kosher. Something is wrong. We know Octavian was Caesars bottom boy. Could it be there was someone behind him....... literally!!