Cristiano Ronaldo stretched his goal-scoring streak to six consecutive league games as Juventus took top spot in Serie A on Sunday with a 2-1 win at Roma, whose defeat was made worse by the cruciate ligament injury of rising star Nicolo Zaniolo.
Juventus move two points ahead of Inter Milan, who were held 1-1 by Atalanta at the San Siro on Saturday, after going two goals up in just 10 minutes in Rome.
Turkish defender Merih Demiral found a way through after three minutes when he connected with a Paulo Dybala free-kick.
Minutes later Argentine Dybala was hauled down in the box, and Ronaldo stepped up to convert from the spot to make it nine goals in six league games.
And Zaniolo was stretchered off in tears eight minutes before the break after falling victim to what Roma later confirmed was a ruptured anterior cruciate ligament in his right knee while trying to dribble past Matthijs De Ligt and Adrien Rabiot.
Diego Perotti pulled a goal back for the hosts from the penalty spot on 68 minutes after an Alex Sandro handball.
However, the capital side drop to fifth, outside the Champions League places, level on 35 points with fourth-placed Atalanta and seven behind local rivals Lazio after their 1-0 win over Napoli on Saturday.
Last season's top scorer Quagliarella gave Sampdoria a third from the spot for his first home goal this season, and added a second in injury time.
In Florence, Patrick Cutrone got his first start for Fiorentina since his move from Wolverhampton Wanderers this week, playing the final 15 minutes in the tight win over rock-bottom SPAL.
German Pezzella struck eight minutes from time to give new coach Giuseppe Iachini his first win for 14th-placed Fiorentina who are now seven points above the drop zone.