Piacenza took a two-goal lead through Gianpietro Piovani and Marco Ferrante before Attilio Lombardo pulled one back near the end from the penalty spot. David Platt was substituted for the second successive match.
Gianluigi Lentini's first appearance of the season could not inspire Milan, who have played three consecutive 0-0 draws in the league. The champions now lead the table with 28 points from 19 matches, three ahead of Juventus and Sampdoria.
Juventus moved level on points with Sampdoria after a goalless draw at home to Roma, during which they had Jurgen Kohler sent off after an altercation with the visitors' Walter Bonacina.
With Paul Gascoigne in fine form again, Lazio moved into fourth place with a convincing 2-0 victory over Reggiana. A fine solo effort from Gianluca Di Matteo and a Roberto Cravero penalty extended Reggiana's miserable away record to eight defeats in 10 matches.
Internazionale recovered from two successive defeats to end Foggia's five-match unbeaten run with a 3-1 win. Uruguay's Ruben Sosa struck first, Wim Jonk added the second and Dennis Bergkamp volleyed a late third, silencing, perhaps only temporarily, the calls for the Inter coach, Osvaldo Bagnoli, to resign.
Another Uruguayan on target was Napoli's Daniel Fonseca, his two goals earned his side a 2-1 home win over Cremonese. Andrea Silenzi, the top scorer in Serie A, struck his 13th goal of the season for Torino, who drew 2-2 at Atalanta.Reuse content