Seven points separates the third-placed Italian champions from Milan, who have picked up 31 points from a possible 33 and are only behind table-topping Napoli on goal difference.
Inter head into the game at San Siro in good form, with four wins and a draw in their last five games in all competitions.
But Inzaghi realises the importance of a fixture where defeat would leave them with a mountain to climb in the title race.
“We are doing great things, the numbers show that. You have to congratulate Napoli and Milan for their progress,” Inzaghi told a news conference.
“Winning tomorrow would increase our conviction, but we will have to all suffer together.”
“We have a big chance tomorrow, We started this run of games (since the October international break) badly with the defeat in Rome against Lazio, then we won (four) and drew one,” he added.
“Those results gave us great conviction, but tomorrow it is fundamental to get a result.”
Milan defeated AS Roma 2-1 last weekend and remained unbeaten in the league this season.
The result in Rome made them the fourth team in Serie A history to win 10 out of 11 games at the start of a league campaign, Napoli being one of the others.
“In these games the league table is reset. We will need to do well in both phases, Milan and Napoli are having a start to the season not seen for 40 years and they deserve praise,” Inzaghi said.
“They give very little away, they have a great coach who I know well, and we will have to pay close attention. We know we are in great form and we can play a good match.”