Coming into Thursday's encounter on the back of three successive 1-1 draws in Serie A, Inter looked to be heading for the same result after Martin Caceres cancelled out Antonio Candreva's 44th-minute opener.

Yet within seconds of Christian Eriksen entering the fray for his Inter bow, the home side retook the lead thanks to a sublime half-volley from Barella.

Napoli now awaits Inter in the last four next month, with Juventus and Milan meeting in the other semi-final.

Pol Lirola and Alexis Sanchez exchanged efforts early on - Fiorentina's wing-back drilling wide before the Inter forward directed a close-range header at Pietro Terracciano.

A tepid first half looked set to end scoreless, but despite creating very little since the opening minutes, Inter had the lead when Candreva slotted into an empty net after Lautaro Martinez had bundled the ball into his path.

Martinez could have turned from provider to scorer moments after the restart but sent a powerful effort into the side netting.

Sanchez was just inches away from putting the hosts 2-0 up when his low strike crept wide, while Martinez sent a half-volley just over.

But just after Terracciano denied Matias Vecino a goal against his former club, Inter were made to pay for their profligacy on the hour as Caceres outmuscled Martinez to head home.

Samir Handanovic pulled off a brilliant save from Dusan Vlahovic to keep the scores level, and Antonio Conte quickly responded by bringing on Eriksen for his debut.

And though he Eriksen was not involved, Inter led less than a minute after his introduction, Barella arrowing a wonderful half-volley into the bottom-left corner.

Martinez later had a goal - teed up by Eriksen - ruled out for offside, but the Nerazzurri sealed progression.