Gotze's strike with just seven minutes remaining in extra time secured the victory for Germany, and Low admits that he always expected substitutes to play a key role in the tense meeting with Argentina.
"We always knew that we would need 14 players during this match and everyone in top shape, and all the players had to be ready," Germany's head coach told FIFA.com.
"It was good that we had played who could come on and make an impact, and Gotze is a miracle boy - a boy wonder. I always knew he could decide the match."
Germany's triumph is the first time a European side has lifted the World Cup in South America.