Inter Milan's bid to defend their Serie A title suffered a setback on Sunday as they were beaten 1-0 at home by Roma, while AC Milan bounced back from their defeat to Atalanta last weekend with a 2-0 victory over Venezia.
The Serie A schedule was adjusted this week, with no matches held on Friday or Saturday due to the funeral of Pope Francis in Rome, meaning the full round of games was moved to Sunday and Monday.
Matias Soule's first-half goal for Roma dropped Inter from the top spot, with Napoli poised to open a three-point lead if they beat Torino later on Sunday.
"Three defeats in one week hurts, and we're not used to such a run," said Inter coach Simone Inzaghi. "It was a very important game, but we lacked a clear head. We need to try and get our energy back, and we'll go to Barcelona with a lot of respect for this team, but without fear."
Argentine Soule stunned the San Siro when he slotted home coolly as the ball ping-ponged around the Inter box in the 22nd minute.
The win moved Roma up to sixth place with 60 points, two off the final Champions League spot.
In another blow for Inter, they risk being without defender Benjamin Pavard for their upcoming Champions League semifinal first leg against Barcelona after the French international limped off in the 15th minute with an ankle issue.
Juventus moved into the fourth and final Champions League qualification spot with a 2-0 victory at home over bottom club Monza.
First-half strikes from Nicolas Gonzalez and Randal Kolo Muani took the Old Lady to 62 points.
However, Juventus will likely be without exciting Turkish forward Kenan Yıldız for their next two fixtures after the 19-year-old was sent off for violent conduct at the end of the first half.
Fiorentina kept their Champions League qualification hopes alive with a 2-1 victory over struggling Empoli.
Goals from Yacine Adli and Rolando Mandragora put the hosts in control inside the opening half-hour, before Jacopo Fazzini gave the 19th-placed side faint hopes of picking up some much-needed points in the 57th minute.
The Tuscany-based club sits in eighth place with 59 points, five ahead of Milan.
In Venice, Christian Pulisic opened the scoring for Milan in the fifth minute, with Santiago Gimenez sealing the victory in the fifth minute of added time at the end of the game.
Milan, who qualified for the Italian Cup final on Wednesday by eliminating bitter city rivals Inter, remain in ninth place.
Venezia stay third from bottom in the relegation zone, one point behind Lecce, who take on third-placed Atalanta on Sunday evening.
Brazilian forward Gabriel Strefezza scored the only goal as Como beat Genoa 1-0 in the duel between former Arsenal players-turned-coaches Cesc Fabregas and Patrick Vieira.
