It appeared as if Empoli was about to pull off an upset in the round of 16 when they went ahead with Nedim Bajrami's strike and an own-goal by home 'keeper Ionut Radu after Alexis Sanchez's opener for Inter.

But Andrea Ranocchia leveled in stoppage time to send the match into extra time, where Stefano Sensi scored the winner.

Inter will next play either Roma or Lecce - the only team outside Serie A left in the competition.

Inter, who lead Serie A, had rotated their squad to give several players a rest.

But coach Simone Inzaghi was forced into an early change when Joaquin Correa limped off in tears with a suspected hamstring problem and was replaced by Sanchez in the fifth minute.

Sanchez had come off the bench to score a last-minute winner against Juventus in the Italian Super Cup last week. And he headed in a cross from Denzel Dumfries in the 13th minute.

Inter had chances to double their lead but Empoli began to get into the match and scored a deserved equaliser when Kristjan Asllani cut the ball back for Bajrami to control and fire into the bottom right corner.

And the turnaround was complete when a towering header from former AC Milan forward Patrick Cutrone bounced off the underside of the bar and in off the back of Radu's leg.

Just as it appeared as though Empoli was about to pull off a shock result at San Siro, Ranocchia levelled with an acrobatic volley from 12 yards.

Sanchez thought he had scored the winner with almost the last kick of the match - as he had done against Juventus - but it was ruled out for offside.

The former Manchester United forward did have a hand in the goal in the 14th minute of extra time. Following a mistake by the Empoli defence, Sanchez set up Sensi - who had only just come on as a substitute.

Sassuolo reached the quarter-finals for the first time in their history with a 1-0 win over Cagliari.

They next faces holders Juventus.

Abdou Harroui scored the only goal of the game in the 18th minute. It was his first goal in Italian soccer after arriving from Sparta Rotterdam in August.

Cagliari had two goals ruled out for offside.

Australian Associated Press