Romelu Lukaku is "giving excellent signals" following a timely return to form, according to Inter head coach Simone Inzaghi.

The Belgium international has scored just four goals for the Nerazzurri since returning on loan from Chelsea last June.

Two of those have come in his last four appearances - including the winner in the first leg of Inter's Champions League last-16 tie with Porto.

The striker is just one goal away from becoming only the fourth player to score 50 times in Serie A and the Premier League, after Gianfranco Zola, Edin Dzeko and Cristiano Ronaldo.

"We know his value, he came from a problematic period, and now he is giving excellent signals," Inzaghi said of Lukaku during his press conference ahead of Inter's clash with Spezia on Friday. 

"He trains in the best way every day, he scored an important goal against Porto, and we want him to continue to raise the condition."

Second-placed Inter will be expected to cut the gap to runaway leaders Napoli to 12 points with victory over their 17th-placed opponents, who are just three points clear of the relegation zone.

The Nerazzurri saw a six-match unbeaten run ended with defeat at Bologna, but Inzaghi was pleased with his side's response in their routine 2-0 victory over Lecce. 

"We reacted well by having an excellent game against Lecce," he added. "We must continue like this, with this determination, also from tomorrow.

"[It will be] a difficult game, against a team that has a very specific goal for which it is fighting.

"They come from two draws in a row. We will have to interpret the game in the best way, doing simple things."