A sloppy Milan side saw their hopes of qualifying for next season's Champions League dented sightly as Sampdoria charged to a slender victory at Stadio Luigi Ferraris on Saturday night.
Milan got off to the worst start possible when Gianluigi Donnarumma's poor pass cannoned against Gregoire Defrel's foot and into the back of the net inside the first minute.
I Rossoneri were poor throughout and struggled to deal with Sampdoria's quick, incisive passing, with Tiemoue Bakayoko's disallowed header the closest the visiting side came to equalising inside the first 70 minutes.
Sampdoria were bright throughout and were denied a second when Fabio Quagliarella's deflected effort cannoned off the bar past the beaten Donnarumma.
The loss means Inter have the chance to pull clear of Milan on Sunday when they face Lazio, while both Roma and Atalanta also have the opportunity to close the gap between themselves and Gennaro Gattuso's side.
Starting XI: Audero (7); Sala (7), Andersen (6), Colley (6), Murru (7); Praet (8), Vieira (7), Linetty (7); Ramirez (6); Quagliarella (6), Defrel (8).
Substitutes: Saponara (6), Jankto (6), Gabbiadini (5)
Key Talking Point
Gennaro Gattuso opted to alter his midfield, with Franck Kessie dropping to the bench after his altercation with Lucas Biglia during the Milan derby and Hakan Calhanoglu featuring centrally with Lucas Paqueta sitting alongside Kessie.
And for the majority of the game, the patched up midfield didn't work. Without Paqueta's flair and Kessie's industry, Milan looked cumbersome and neither Suso or Samu Castillejo saw enough of the ball to trouble Sampdoria's backline or link up with Krzysztof Piątek.
The visitors huffed and puffed in the closing stages, with Patrick Cutrone and Paqueta brought on to try and affect the game, but Sampdoria held firm to secure a big win for their own European qualification challenge.
Starting XI: Donnarumma (4); Calabria (6), Musacchio (5), Romagnoli (5), Rodriguez (6); Bakayoko (6), Biglia (5), Calhanoglu (5); Suso (5), Piatek (5), Castillejo (5).
Substitutes: Conti (6), Cutrone (5), Paqueta (5)
STAR MAN - Given that it was a pretty poor performance from Milan all round, it's tricky to single out one player in particular for praise.
Davide Calabria and Ricardo Rodriguez were reasonably industrious in their respective full back positions, but neither man will be boasting about their performance on the journey back to Lombardy.
Sampdoria will continue their push for European qualification when they face Torino on Wednesday, before a home clash with Roma.