The 39-year-old striker has scored 10 goals in six league games to be essential in the Rosonnerri’s great start to the season.
Although Milan have continued their great form in Ibrahimovic’s absence, Diaz believes the Swede can now play a pivotal role off and on the pitch after making his comeback on Saturday, coming off the bench in the closing stages of a 2-0 win over Torino.
"Ibrahimovic is a player who makes the difference," Diaz said in an interview with Sky Sport Italia.
“He transfers his great experience to us. Now that he is back, we will do great things.
"He has a winning mentality and forces you to always give your best, he wants the best of ourselves every day."
The Spaniard, who made his eighth league start against Torino, played a major role in Milan’s victory over Torino. The 21-year-old winger provided the assists for Rafael Leao and then, won a penalty for Rosonnerri’s second goal.
The victory moved Milan four points clear at the top of the Serie A’s table, and they’re hoping to crown the league title for the first time in a decade.
"We are Milan, this word is enough to understand that we always want to win, then we'll see," said Diaz, who is on loan from Real Madrid.
"We can dream. We are a very united group and we want to do great things together. The best is yet to come, we are all fine and also I feel great.
"I am happy for the penalty which I won, for the assist and for the three points against Torino. If we continue like this, little by little we will be able to do more and more."