Table-toppers Juventus were held to a 1-1 draw against Lecce in the Serie A on Wednesday while AC Milan defeated Atalanta 2-0.
Juve, who entered the match on the back of seven successive wins, looked in for a comfortable night when Claudio Marchisio opened the scoring after just nine minutes.
Marchisio converted Andrea Pirlo's assist and Juventus seemed headed for another victory in what has been a remarkable season.
But although their unbeaten record in competitive matches - which is now 41 - continued, they could not win all three points at Juventus Arena.
That was despite Lecce's Colombian midfielder Juan Cuadrado being sent off for a second yellow just nine minutes into the second half.
Juventus failed to make their numerical advantage count and were made to pay when substitute Andrea Bertolacci equalised with just five minutes remaining.
Juve's failure to win, coupled with Milan's triumph, means Antonio Conte's men lead the league by just one point with two matches to play.
Milan's win came thanks to goals from Sulley Muntari and Robinho, with the latter in stoppage time as Atalanta made the second-placed side work for the three points.
Udinese are level on points with third-placed Napoli in the fight for a spot in the playoffs for next season's UEFA Champions League after they won 1-0 at already relegated Cesena.
Diego Fabbrini scored the only goal of the game after just four minutes for Udinese.
Cesena forward Adrian Mutu missed a 21st minute penalty as Francesco Guidolin's men left Stadio Dino Manuzzi with all three points.
Parma won their fifth match in a row after they came from behind to defeat Inter Milan 3-1.
Wesley Sneijder's 13th minute effort separated the two sides at the break but goals from Fernando Marques, Sebastian Giovinco and Jonathan Biabiany in the second half saw Roberto Donadoni's men win again.
Cristian Ledesma's second-half penalty gave fifth-placed Lazio a 1-1 draw with Siena while Genoa notched a much-needed three points in their bid to avoid relegation with a 2-1 home success against Cagliari.
And despite Riccardo Montolivo's second-half double giving Fiorentina a 2-2 draw with Novara, the Florence-based club still sacked manager Delio Rossi.