Napoli had a thumping 5-1 win over bottom club Pescara but Inter scraped an unconvincing 1-0 victory at home to Palermo.
Two goals each by Gokhan Inler and Edinson Cavani, one from the penalty spot, helped Walter Mazzarri's Napoli side stay two points behind Juve, who defeated local rivals Torino 3-0 on Saturday.
Inter are four points behind Juve on 31 after ending a run of three games without a win thanks to an own goal by Palermo's Santiago Garcia.
Stefan Savic scored both Fiorentina goals in a 2-2 draw which earned a point after Nenad Krsticic and a Gonzalo Rodriguez own goal had seen Sampdoria equalise then take the lead. Savic's goals were his first in Serie A.
"Honestly I'm happy with our position, it's a shame that it's not the end of the season now, or at least within a couple of games," Fiorentina coach Vincenzo Montella told reporters.
"We came up against a Sampdoria side that caused us problems, and while we weren't brilliant we had enough opportunities to win.
Fiorentina are in fourth place, level on 29 points with Lazio and two behind Inter Milan as Samp moved up to 12th on 17.
Lazio are six points off the pace in fourth spot after beating Parma 2-1 thanks to a 25th-minute effort from defender Giuseppe Biava and Miroslav Klose's ninth league goal of the season.
Ishak Belfodil pulled one back for Parma in the 66th minute, converting the rebound after his penalty was saved.
AS Roma are sixth after coming back from a goal down to win 3-1 at lowly Siena.
Two goals from rejuvenated former Siena striker Mattia Destro and one by Simone Perrotta gave Zdenek Zeman's side a deserved victory in a match where they missed a hatful of chances.
A first half hat-trick from Alberto Paloschi and a last minute tap-in by Adrian Stoian gave Chievo a 4-2 victory at fellow strugglers Genoa and their first away points of the season.
Genoa's fourth straight home defeat left them in the bottom three on 12 points, only one ahead of Pescara.
Bologna beat Atalanta 2-1 thanks to a deflected free-kick from Alessandro Diamanti in the 16th minute and a second-half goal from former Atalanta player Manolo Gabbiadini while Udinese stayed in mid-table despite a 4-1 rout of Cagliari.
