Napoli failed a big test of their Serie A title credentials as they lost 2-1 at home to Udinese to pave the way for Milan to clinch the Scudetto.
The hosts needed to win at the Stadio San Paolo to make it a two-horse race for the title after Inter slipped up yesterday, but they instead remained six points adrift of the league leaders with five games remaining.
Udinese, who won thanks to goals from Gokhan Inler and German Denis, boosted their own chances of qualifying for the Champions League next season by reducing the arrears on fourth-placed Lazio to just one point.
Edinson Cavani had a penalty saved in the dying stages of the match after Maurizio Domizzi was sent off for Udinese, before Giuseppe Mascara scored a consolation deep into stoppage time.
Lazio had earlier recorded a convincing 4-1 victory at Catania.
Hernanes put Lazio ahead before Matias Ezequiel Schelotto equalised soon after half-time.
Stefano Mauri, Sergio Floccari and substitute Mauro Zarate got the other Lazio goals at the Angelo Massimino Stadium.
Juventus lost further ground on the European qualification places as they were held to a 0-0 draw at Fiorentina, meaning they are now eight points behind fourth-placed Lazio.
Goals by Kevin Constant and Michele Marcolini saw Chievo overcome the sending off of Luca Rigoni as they closed to within one point of Bologna with a 2-0 win.
Constant enjoyed an easy tap-in to put the hosts ahead after 15 minutes before Rigoni was given a straight red card for a professional foul in first-half injury time.
However, they managed to extend their lead seven minutes from time when Marcolini produced a superb lob to collect only their fifth home win of the season.
Genoa returned to winning ways at the Stadio Luigi Ferraris to do their city rivals Sampdoria a favour by defeating relegation-threatened Brescia 3-0.
Genoa took their guests apart in the second half with goals from Rafinha, Luca Antonelli and an own goal from Gaetano Berardi.
Brescia remain in the bottom three, four points adrift of safety while Genoa are safe in mid-table with 42 points.
Lecce salvaged a point in their Serie A survival scrap with a dramatic injury-time equaliser from Daniele Corvia in the 3-3 draw with Cagliari.
Lecce trailed 3-1 before Medina Fabiano pulled one back and Corvia smashed in the equaliser.
Robert Acquafresca gave Cagliari the lead but Djamel Mesbah equalised in the second half.
Daniele Conti put Cagliari back in front and Acquafresca netted again to increase the lead before Fabiano and Corvia ensured Lecce shared the points.
Erjon Bogdani's second-half goal handed Cesena victory in their battle to avoid relegation while it placed Bari one step closer to Serie B.