Monza had an 81st minute lead through Dany Mota Carvalho, but were pegged back by Denzel Dumfries on 88 minutes.
Inzaghi said afterwards: “The first 20 minutes were very good, we created a lot of chances and should’ve broken the deadlock then. It was quite similar last season, but we took the lead early and didn’t do it this time.
“After that, we were a bit slow in moving the ball around, didn’t have enough quality in the final ball and should perhaps have tried shooting rather than going for the assist. Monza defended very deep, we should’ve done better to steer the match in our direction.
“Just as we were attacking with an extra striker, we conceded a great goal from Dany Mota. It was truly a wonderful leap. Fortunately, we did well to equalise and then had a chance to win it with Frattesi.
“We’re disappointed but we go forward.”