Chievo secured Serie A safety as Catania, Bologna and Livorno were condemned to relegation and Juventus set a new points record.
Dario Dainelli's 72nd-minute strike earned Chievo a 1-0 win over Cagliari and kept Eugenio Corini's men in the Italian top flight after a run of three straight defeats had brought them to the brink of the drop zone.
With just one game to go, the bottom three sides now have an insurmountable gap to close and will all play in the second tier next term.
But it was a day of celebration for champions Juventus, who beat Roma 1-0 to reach 99 points, surpassing Inter's previous record of 97.
Antonio Conte's men left it late, substitute and former Stadio Olimpico favourite Pablo Daniel Osvaldo scoring his first Serie A goal of the season four minutes into stoppage time to ruin Roma's unbeaten home record this term.
There was controversy, too, as Italy defender Giorgio Chiellini appeared to elbow Miralem Pjanic, though referee Carmine Russo did not take any action.
If the authorities decide to look at the incident and find Chiellini guilty, he could fall foul of national coach Cesare Prandelli's rule of not picking players who have suffered disciplinary issues, therefore throwing his FIFA World Cup dreams into disarray.
At the other end of the table, Catania scuppered Bologna's survival chances as both sides were demoted following a 2-1 win for the visitors.
Catania, who beat high-flying Roma last Sunday, led through Fabian Monzon when Gino Peruzzi saw red for a second booking, and Bologna capitalised to level the scores 11 minutes from time through Archimede Morleo.
But Gonzalo Bergessio hit back for the away side just five minutes later and Daniele Paponi's dismissal saw the match finish 10-a-side.
Livorno, winners of the Serie B play-offs last season, completed the relegation picture with a 1-0 home loss to Fiorentina, Miguel Borja's sending off compounding the hosts' misery.
Fellow top-flight newcomers Sassuolo hit four goals for the second game running to beat Genoa 4-2 and confirm their survival.
Franco Brienza fired home a stunning late winner as Atalanta beat Milan 2-1 to dent the latter's bid for European qualification.
Sadly, matters on the field were marred by a banana being thrown onto the pitch in the direction of Milan defender Kevin Constant, an action that was met with sarcastic applause from team-mates Philippe Mexes and Nigel de Jong.
Milan can still claim sixth, which will be enough for a UEFA Europa League spot, as Torino drew 1-1 with Parma in a match that saw both sides finish with 10 men.
Napoli produced one of the performances of the day by putting five past Sampdoria.
Duvan Zapata, Lorenzo Insigne, Jose Callejon and Marek Hamsik were all on target, with Shkodran Mustafi's own goal adding to Sampdoria's woe in a 5-2 loss.