A frenetic first-half display by Simone Verdi ended Inter Milan's perfect start to the Serie A season as shaven-headed skipper Mauro Icardi rescued a 1-1 draw at Bologna.

Luciano Spalletti had been looking to make it five wins from five but had to settle for just one point in Bologna.

Verdi came out firing on all cylinders with a half dozen shots at goal before the breakthrough on 32 minutes with a powerful long-range effort.

But Argentine forward Icardi -- sporting a new shaven head -- levelled from the spot after 77 minutes after a contested foul by Ibrahima Mbaye on Eder.

"It's not a scandal for a team to draw," said Spalletti.

"We were slower than usual, unable to make the ball move well in vertical lines, especially in midfield, so we gave Bologna the chance to close down our channels."

Verdi's was just the second goal conceded this season by Inter, who had been sitting top on maximum points alongside Napoli and Juventus after four matches.

Now with 13 points, Inter move provisionally top but champions Juventus and Napoli have the chance to pull ahead when they play Fiorentina and Lazio respectively on Wednesday.

"We knew that Bologna is a team that plays well," said Inter striker Eder.

"There are two lost points, we will see what went wrong this week."

Eder added: "We have to look at ourselves not Napoli and Juventus, our goal is the Champions League and we have to fight at all costs."

Spalletti had made just one change to the side that beat Crotone on Saturday with Japanese defender Yuto Nagatomo in for Brazilian Dalbert.

But Inter suffered in the first half with Argentine Icardi just failing to get on the end of an Ivan Perisic cross before Verdi got on the scoresheet.

Inter gained momentum after the break but failed to find a way through until the controversial foul by Mbaye on Eder which was confirmed by the video assistant referee.

Eder won the spot-kick, as he was running away from goal when Mbaye tripped and accidentally landed with his arm on the forward's heel.

Icardi converted the penalty for his sixth goal of the season to snatch a point ahead of Sunday's second Serie A fixture this week against Genoa in the San Siro.

"He scored tonight, so we'll shave his head every day now," joked Spalletti.

Bologna move up two spots to 11th as they bounced back from the weekend defeat at Fiorentina.

"We deserved something more, on the pitch we showed it," said Verdi. "There are still many doubts about that penalty."