Inter Milan ended Napoli's unbeaten start to the Serie A season after coming from behind to earn a thrilling 3-2 victory at the San Siro on Sunday, closing the gap to the leaders to four points.
The game was played at a ferocious pace, with Napoli storming into an early lead thanks to a powerful Piotr Zielinski strike in the 17th minute.
Inter put themselves in command just after the hour mark, with Argentine striker Lautaro Martinez applying the finishing touch to a swift counter attack.
Dries Mertens got Napoli back into it with 12 minutes left, but it was not enough to prevent Luciano Spalletti's leaders slipping to a first defeat in 13 Serie A games this term, as third-placed Inter laid down a marker in the title race.
"Today we had to show what we are capable of," Martinez told DAZN. "We do things well, but sometimes the result doesn't work in our favour. We had an intense match, and with character, we got the points we need."
Inter were determined to put Napoli on the back foot right from the off, raining in 13 shots on the visitors' goal in the first half alone.
Against the run of play, Zielinski's strike edged the visitors in front, as Napoli gave themselves a chance of pulling clear of AC Milan in second, after Stefano Pioli's side suffered their first Serie A loss of the season at Fiorentina on Saturday.
Inter, however, just could not be kept at bay. Kalidou Koulibaly's handball gifted them a way back into the contest, with Calhanoglu making no mistake from the spot, before Perisic's flicked header just crossed the line to give Inter the lead.
Napoli were dealt a blow early in the second half when top goalscorer Victor Osimhen was forced off with a nasty head injury, and it was Inter's talisman, Martinez, who compounded the visitors' woes with his fine goal.
Substitute Mertens scored the goal of the match to give Napoli a real chance of salvaging a point, curling in from 25 yards, and Mario Rui almost levelled in dramatic fashion in stoppage time, but it was not meant to be for the table toppers.