Internazionale coach Roberto Mancini was delighted after his side registered their third consecutive win of the season.
Fredy Guarin's second half goal was enough for the Nerazzurri to battle past rivals Milan.
And Mancini believes the win will inject confidence and belief in his players.
"Winning the derby in the third match of the season is important because teams haven't found their best form yet," Mancini said after the game.
"This win should give us added belief in our ability and help us to work calmly but we know there's still a long way to go. It's our duty to aim for the very top because we're Inter.
"It's a long season and we have a lot of work to do. Great teams should always aim to win but then you need to put in the effort and also have a bit of luck go your way.
"We'll see what happens. At the moment Juventus, Roma and Napoli are better equipped than we are.
"Medel started in defence because he's an experienced, smart player who's used to playing in that position. He knows when to take a step back and when to nip in ahead of his man.
"I went with him because he knows Milan's two strikers well and because he plays in a back four for Chile. Andrea [Ranocchia] hasn't played much and wasn't 100%."