Inter, two points behind fierce rivals AC Milan going into the game with a game in hand, took the lead after just three minutes through Ivan Perisic.
Marko Arnautovic restored parity 25 minutes later.
Ionuț Radu then produced a monumental howler with nine minutes of normal time remaining.
The Romanian, making his first appearance in Serie A this season and filling in for the injured Samir Handanovic, received the ball on his goalline.
Radu was being quickly closed down Nicola Sansone and disaster struck when he completely missed his kick.
Sansone then had the easy task of putting the ball into the net from a few inches out. It was an awful error by Radu and you can watch it below…
CATASTROPHIC! 😲— Football on BT Sport (@btsportfootball) April 27, 2022
It's a nightmare for Inter Milan's second choice goalkeeper, Ionuț Radu.
Could that cost them the Serie A title? pic.twitter.com/7NcXOxiMwZ
Inter could not find an equaliser and fell to a what could prove to be a costly defeat.
Simeone Inzaghi spoke about Radu’s mistake in his post-match interview.
He said, per football-italia: “Radu played very well against Empoli, he always trains well, we all have the utmost faith in him. It was an unfortunate incident, but these things can happen and it wouldn’t have been as damaging if we’d been 4-1 up rather than at 1-1.
“He should be reassured that Radu is an excellent goalkeeper with a bright future ahead of him.”
It’s now advantage AC Milan in the race for the Scudetto.
Inter find themselves two points behind their city rivals with four games remaining.
Inter and looking to win their second consecutive Serie A title, while AC Milan are bidding to be crowned Italian champions for the first time since 2011.