Romelu Lukaku warned his Inter teammates they still have plenty of room for improvement after the Belgian’s extra-time header secured victory against Fiorentina in the Coppa Italia.

Antonio Conte’s side led at half-time following a penalty scored by Arturo Vidal, but former Nerazzurri academy talent Christian Kouame levelled the match at the Stadio Artemio Franchi and forced an additional 30 minutes.

Inter seemed set for a penalty shoot-out in Florence before Lukaku turned in Nicolo Barella’s cross in the 119th minute, setting up a quarter-final clash against city rivals AC Milan.

“The derby comes in the future, today we are happy to have won a difficult match with a great coach,” Lukaku told Italian broadcaster Rai Sport following the full-time whistle.

“We are happy and we want to continue like this.”

Lukaku was then asked about the difficulties that Inter as team experienced during the second half and admitted that there is a desire within the team to get better.

“The difficulties in the second half? I don’t know why it happens, we already said it after the draw against Roma that it shouldn’t happen but it happened even if we still won this time,” he admited.

“We are young, we must learn from these things but we want to improve.”

The prolific Belgian national team forward then looked ahead to this weekend’s Derby d’Italia match-up with Juventus in Serie A, which will be the first time the arch-rivals lock horns this season.

“I expect a tactical match between two teams who are doing good things.

“Juventus are a big team, we want to prepare well for this match.”