Lazio won 2-1 to be sure of a top four finish.
“It was a magical and important evening," Inzaghi told DAZN. “After 13 years it's something unimaginable but we had confidence.
“To be honest, despite the disadvantage, I was calm today. I had players on the bench who could change the match."
Inzaghi added: “We must improve, I'm lucky to have (Igli) Tare as sporting director and he knows what he's doing. He has been working well in these years.
“We have an excellent relationship and I have great faith in him."