AC Milan were held to a spectacular 3-3 draw at struggling Sassuolo on Sunday to leave Inter Milan within touching distance of the Serie A title ahead of their late fixture with Cagliari.
Noah Okafor salvaged a hard-fought point for Milan in the 84th minute on a hot spring day in Reggio Emilia, but second-placed Milan still risk conceding the Scudetto to Inter in a hotly-anticipated derby despite coming back from two goals down.
Milan, who also netted through a sublime individual goal from Rafael Leao and Luka Jovic's close-range finish, are 13 points behind their local rivals with six fixtures left in their season.
Should Inter beat Cagliari at the San Siro as expected, the champions-elect would only need to draw with Milan on Monday week in order to secure their 20th league crown.
That would be a bitter pill to swallow for Milan, who have never been in the title race this season as Inter have charged off into the distance since the turn of the year.
"We created more opportunities than in any match this season, if we'd had scored five or six goals no-one could have said anything," said Milan coach Stefano Pioli.
"But we have to be better because our coming matches demand a higher level of performance."
Pioli made a raft of changes in the wake of a first-leg defeat to Roma in the Europa League quarter-finals and were two goals behind with less than 10 minutes on the clock following early strikes from Andrea Pinamonti and Armand Lauriente.
Frenchman Lauriente's second seven minutes after the break -- which re-established Sassuolo's two-goal lead after Leao struck in the 20th minute -- enabled second-from-bottom Sassuolo to move to within two points of safety.
Now Milan's return leg in Rome on Thursday takes on even more significance as failing to overturn a single-goal deficit in that tie would be a huge blow ahead of the Milan derby and then a trip to third-placed Juventus the following weekend.
"I believe 100 percent in my team, we have men of quality, we are a really good team," said goalscorer Okafor.
"Now have to focus... for sure we are going to Rome to win."
- Napoli slip -
Napoli's slim chances of Champions League football were dealt another blow after a 2-2 home draw with struggling Frosinone.
Walid Cheddira's first brace in Italy's top flight earned a point for Frosinone at Napoli, who were on target through Matteo Politano and Victor Osimhen.
The draw left ailing Italian champions Napoli in eighth with six games remaining, six points behind fifth-placed Roma who can extend their advantage when they face Udinese later on Sunday.
Italian clubs' strong performances in European football mean a top-five finish in Serie A is almost certain to gain a spot in the Champions League.
Francesco Calzona's Napoli are increasingly unlikely to be among that group, and were booed off the pitch at a sparsely-populated and roasting hot Stadio Diego Armando Maradona.
"We didn't manage the game well enough when we went ahead. I asked for them to keep it simple because with this heat it was very difficult," said Calzona.
"We've conceded too many goals this season... we allowed the game to stay open and that's what worries me the most. I don't understand why we don't seem to perceive danger."
Frosinone stay just inside the bottom three and level on 27 points with 17th-placed Verona, who are outside the relegation zone on goal difference and face Atalanta on Monday.
Eusebio Di Francesco's team have only won one league match since late November but successive draws with Genoa, fourth-placed Bologna and now Napoli have boosted their hopes of staying up.
By Terry Daley