Inter Milan captain Mauro Icardi missed a 26th-minute penalty as the Nerazzurri were beaten 2-1 by Cagliari.
Icardi had been jeered and greeted with derogatory banners as he walked out ahead of the match after angering Inter ultras with comments in his autobiography and his miss from the spot was cheered.
Joao Mario gave Inter the lead 10 minutes after half-time, but Federico Melchiorri levelled in the 71st minute and had a hand in the second, five minutes from time, as his deflected cross was turned into his own net by Inter goalkeeper Samir Handanovic.
Melchiorri has now scored two goals in his only two Serie A matches after a difficult few years that saw him undergo brain surgery and also return from a serious knee injury.
Cagliari, who won Serie B last season, moved above Inter into seventh spot.
AC Milan extended their unbeaten run against Chievo to 20 matches and climbed up to third in the table with a 3-1 win on the road.
Juraj Kucka and M'Baye Niang struck quickfire goals either side of half-time and although Valter Birsa gave Chievo hope with a second-half free kick, Dario Dainelli's own goal in stoppage time settled the issue.
Milan held on to make it five games unbeaten and became the first side this season to win a league game at Stadio Marc'Antonio Bentegodi.
Lazio could have moved second but they needed a controversial last-gasp penalty to rescue a 1-1 draw against Bologna.
Bologna took the lead in the 10th minute when Simone Verdi whipped in a free kick from the right flank and Filip Helander stretched out a leg to poke it past Federico Marchetti at the far post.
Lazio, who also hit the woodwork, thought they had levelled in the 69th but goal-line technology showed the ball had not crossed the line -- sparing the blushes of Erick Pulgar, whose backpass set up the chance.
The capital club did level in the sixth minute of stoppage time when Ciro Immobile converted from the spot with the last kick of the game. However, television replays showed it was a harsh decision against Bologna defender Marios Oikonomou because Lazio defender Wallace appeared to dive.
Sassuolo survived a scare to record a late comeback victory as they edged bottom side Crotone 2-1.
The Serie A newcomers took an early lead after just two minutes as loanee Diego Falcinelli slotted Aleandro Rosi's cross home from the centre of the box to see his parent club fall behind.
The Black and Greens dominated possession and finally saw their hard work pay off when Stefano Sensi picked out the bottom corner after 83 minutes. Lorenzo Pellegrini set up Pietro Iemmello to complete the fightback as he netted a close-range winner three minutes from time.
Atalanta ended their nine-game losing streak against Fiorentina with a goalless draw.
The Bergamo club's losing run against Fiorentina dated back to 2012 and they might have even had a first win at the Stadio Artemio Franchi for 23 years after spurning the best chances of the game.
Jasmin Kurtic's angled drive was cleared off the line when Fiorentina goalkeeper Davide Astori stuck out a toe, while an Andrea Conti pull-back narrowly failed to pick out his teammates in the centre of the penalty area.
Nikola Kalinic blazed over when Fiorentina's best opportunity arrived in the first half after a good run. The Viola have yet to concede a home league goal in five games this season, but have scored just twice.
Genoa extended their unbeaten run in Serie A to four matches but were held to a goalless home draw by Empoli after midfielder Darko Lazovic had been sent off.
Lazovic was shown a second yellow card for his foul on Manuel Pasqual in the 34th minute of a game devoid of much goalmouth action.
Information from The Associated Press and the Press Association was used in this report.