Rafeal Leao and Davide Calabria struck to pull AC Milan back from a dismal first-half display which left them trailing to a Theo Hernandez own-goal and Federico Baschirotto's well-placed header in a 2-2 draw away at Lecce.
Stefano Pioli's side showed fight to level against promoted Lecce, who beat Atalanta and Lazio in their last two matches at the Stadio Via Del Mare.
But the draw, which moved second-placed Milan a point above Juventus who were ripped to pieces by Napoli on Friday night, concludes a poor week which has severely compromised their bid to retain the Scudetto.
It comes after throwing away a two-goal lead in the final minutes against Roma last weekend and then being dumped out of the Italian Cup at the last 16 stage by 10-man Torino midweek.
"We'll believe in it right until the end. Now we need to look at what we did badly and what we did better," said midfielder Ismael Bennacer when asked if Milan still had hopes of holding on to their title.
"We're a good team, when we have these problems we're capable of resolving them on the pitch."
Milan, who travel to Saudi Arabia for Wednesday's Italian Super Cup against Inter Milan, now only lead their local rivals by a point after Lautaro Martinez shot them to a 1-0 win over struggling Verona.
The seven-time European champions were lucky to be only two goals down at the break of an entertaining match as Lecce had two great chances to secure an unassailable lead.
Federico Di Francesco slid wide from close range early on before clipping in a perfect cross for Valentin Gendrey who headed wide with the goal at his mercy in the 26th minute, at which point the hosts were already two ahead.