WATCH: Derby delight for dominant Inter

The Nerazzurri moved four points clear at the top of Serie A thanks to a double from Martinez and Romelu Lukaku's 23rd goal of the season in all competitions.

Lukaku crossed for his strike partner to nod in after only five minutes and each of them scored after the interval to put the game beyond Milan's reach.

Having been eliminated from European competition in December and beaten in the Coppa Italia semi-finals by Juventus, the Scudetto remains Inter's only hope for silverware in 2020-2021.

Martinez is now determined to end the club's 11-year wait to become champion of Italy again.

"This is what we are: we're united, we work every day to give our best and to reach as high as we can, and today we proved it," Martinez said.

"We run and fight together; you can see it on the pitch. We have suffered a lot this year: two eliminations from the Coppa Italia and the Champions League. This [Serie A] is the only goal left and we're fighting for it. We're happy to be ahead of everyone else."

Lukaku became the first Inter player since Benito Lorenzi in 1950 to score in four consecutive league derbies against Milan.

Martinez believes the Belgium international can still get better as he aims to win a first club trophy since the Belgian Pro League with Anderlecht in 2010.

"Lukaku can improve a lot," Martinez said. "He's 27 years old, he works and he makes himself available to his team-mates. He's a great person on and off the pitch and we're happy to have him with us."

Inter were mostly in control of the contest but were indebted to goalkeeper Samir Handanovic in the first three minutes of the second half, as he twice denied Zlatan Ibrahimovic in quick succession before tipping a Sandro Tonali shot over the bar.

"Handanovic is always ready. We're happy because, when we need him, he always responds," Martinez said.

"We also should have been more focused [early in the second half], but we're happy to have played a good game and to have got three points."