Hernanes' goal half an hour into a scrappy match with struggling Samp sent Vladimir Petkovic's team up to 36 points, eight behind champions and league leaders Juventus, who won 3-1 against Cagliari on Friday.
Andrea Stramaccioni's Inter dropped to fourth place after Esteban Cambiasso's equaliser five minutes from time cancelled out Ciro Immobile's superb individual goal for second-bottom Genoa. [REPORT]
Two Stevan Jovetic goals either side of halftime and a second penalty from Gonzalo Rodriguez were enough for Fiorentina to win 3-0 at troubled Palermo.
Vincenzo Montella's dark horses moved above Inter into third, on the same points as the Nerazzurri and one behind Lazio.
Napoli, who were docked two points in midweek for the involvement of their players in a betting and match-fixing scandal from 2010, scored two goals in the last five minutes in a dramatic 2-0 win at bottom club Siena.
Christian Maggio netted before Edinson Cavani converted from the spot.
Walter Mazzarri's side were far from their thrilling best but stay in fifth and within two points of Lazio, putting pressure on the other challengers for the Champions League places.
German Denis' 40th-minute penalty, his seventh goal of the season for Atalanta, helped the hosts draw 1-1 with Udinese, who had taken the lead seven minutes previously through Luis Muriel's first of the campaign.
Torino comfortably saw off Chievo 2-0 in Turin while Frederik Sorensen's goal for Bologna nine minutes into the second half was cancelled out by Jaime Valdes two minutes later before Nicola Sansone netted on 66 minutes to give Parma a 2-1 away win.
Serie A stops for a mid-season break after this weekend until January 5.