Roma fell to their first defeat in Serie A since Nov. 1 to see their grasp on a place in the Champions League next season loosen with a 2-0 loss at home to Sampdoria.
Lorenzo De Silvestri and Luis Muriel grabbed the goals for the Blucerchiati, who weathered a first-half storm before striking efficiently in the second half to boost their own hopes of qualifying for Europe next season.
On the hour mark, Samuel Eto'o pulled the ball back to the edge of the six-yard box where De Silvestri had all the time in the world to turn it in.
Muriel then raced almost 50 yards with the ball at his feet before curling his shot against the right-hand post, then swept it in at the second attempt.
Roma's sorry evening ended on an even worse note with Seydou Keita shown a red card late on as the Giallorossi also helped Juventus get one hand on a fourth straight Serie A title, thanks to their 14-point advantage with 11 games remaining.
Felipe Anderson scored twice to give Lazio a 2-0 win at Torino as Stefano Pioli's side closed the gap on second-placed Roma to just one point.
Lazio won their fifth straight game in the league and moved three points clear of Napoli in the race for the Champions League spots as well as closing in on their city rivals, who hosted Sampdoria later.
Felipe Anderson netted his double in seven second-half minutes to take his tally to eight league goals this season.
He broke the deadlock in the 71st minute on a counter which saw him dribble his way through three players before driving into the bottom left corner.
The Brazilian doubled his tally after running onto Miroslav Klose's pass and beating Daniele Padelli from a tight angle.
Two late goals helped Fiorentina come from behind to beat AC Milan 2-1, with Gonzalo Rodriguez and substitute Joaquin scoring inside the final seven minutes to cancel out Mattia Destro's opener.
Milan had won just one of their past five matches but looked set to pull off a surprise victory after Destro redirected Giacomo Bonaventura's wayward shot in the 56th minute.
However, Fiorentina -- who had hit the bar in the first half with a Jose Maria Basanta header -- turned the game around in the 83rd minute when Gonzalo Rodriguez headed home Joaquin's cross before the Spaniard got on the scoresheet himself in the final minute with another header.
It was the first time Milan had lost at Fiorentina in nearly 10 years. Fiorentina moved a point behind Napoli, while Milan remained 10th.