Olivier Giroud’s goal second before the break was not enough for Milan to beat Salernitana as a Boulaye Dia strike in the second half stunned the Rossoneri.
Junior Messias was the only player not available for Milan, while Salernitana travelled to San Siro without William Troost-Ekong.
Sandro Tonali was initially on the bench, meaning the Rossoneri started their first-ever Serie A match with no Italian players in their line-up.
Milan had the first chance of the match with Rafael Leao who sent a curler wide of the far post. Giroud had a second opportunity a few minutes later with an overhead kick sent over the crossbar.
Salernitana struggled to put the noses out of their own half, but when they did it, Boulaye Dia found himself face-to-face with Mike Maignan after making the most of a misplaced pass from Malick Thiaw. However, the Senegal international could not even shoot as he was stopped by the France goalkeeper just outside the box with a Baresi-esque tackle.
Giroud broke the deadlock seconds before the break emerging at the near post from a corner kick and beating Ochoa.
The France striker was given his fifth yellow card this season in the second half, meaning he will miss next week’s match against Udinese but will be available for Napoli after the break.
The Rossoneri had a slow start in the second half and allowed the visitors to level the score through Dia who received a Domagoj Bradaric pass from the left, finding the net from inside the box at the near post.
Ismael Bennacer earned a penalty kick for a suspected foul of Bradaric, but it was soon overruled after an on-field review of referee Federico La Penna.
Pioli’s men pushed for the winner, Ochoa produced at least two decisive saves on Divock Origi and Zlatan Ibrahimovic, but the defending Serie A champions had their best chance with Alessandro Florenzi whose shot was accidentally stopped by his teammate Pierre Kalulu while the ball was about to cross the line.
Milan remain fourth with 48 points, one more than Roma in firth, while Salernitana are now seven points clear of 18th-placed Hellas Verona in the relegation zone.
Milan 1-1 Salernitana
Goals: 45+1’ Giroud, 61’ Dia.
MILAN (3-4-2-1): Maignan; Kalulu, Thiaw, Tomori; Saelemaekers (77’ Florenz), Bennacer (85’ Tonali), Krunic, Theo; Diaz (62’ De Ketelaere), Leao (62’ Origi); Giroud (62’ Ibrahimovic).
SALERNITANA (3-4-2-1): Ochoa; Daniliuc, Gyomber, Pirola (68’ Lovato); Mazzocchi (83’ Sambia), Coulibaly, Bohinen (83’ Crnigoj) , Bradaric; Candreva (68’ Bonazzoli), Kastanos (56’ Piatek); Dia.