(CNN) -- Sampdoria moved to the top of Italy's Serie A with a 4-1 trouncing of Siena as city rivals Genoa dropped their first points after losing 3-1 at Chievo.
Two-goal substitute Marco Padalino celebrates after making it 3-0 for Sampdoria against Siena.
The Blucerchiati climbed above Juventus on goal difference, with both teams on a perfect 12 points from four matches this season after the Turin side's 2-0 win against Livorno on Saturday.
Defending champions Inter Milan are third, two points back, after beating Cagliari 2-1, while Genoa plummeted to fourth after losing their 100 percent record.
AC Milan were one of four teams on seven points after a 1-0 victory at home to Bologna.
Sampdoria took the lead after 23 minutes at home to Siena as Angelo Palombo beat two defenders and lashed as shot past goalkeeper Gianluca Curci.
Daniele Mannini doubled the lead eight minutes later after combining with Antonio Cassano, while substitute Marco Padalino made it 3-0 three minutes after halftime from close range after Curci blocked Cassano's effort.
Michele Fini pulled one back midway through the second half but Padalino made it safe five minutes from the end, again pouncing on a rebound as Curci could not hold Giampiero Pazzini's shot.
Inter, held 0-0 by Barcelona in the Champions League in midweek, went behind in the 16th minute as Jeda converted a penalty for the Sardinians, but summer signing Diego Milito netted twice in the space of four second-half minutes to secure victory.
The Argentine leveled in the 51st minute and then lobbed home a second goal to give the Nerazzurri a third win in four league games.
His former club Genoa conceded two goals in the first seven minutes at Chievo, and also missed a late penalty.
Michele Marcolini converted a fourth-minute penalty after a foul by Giuseppe Biava on Erjon Bogdani, who soon doubled the lead from close range after being set up by Luciano.
Sergio Floccari reduced the deficit with a penalty in the 65th minute when Mario Yepes handled the ball, but Sergio Pellissier made it 3-1 on 76 with a close-range header after Pablo Granoche flicked on Giampiero Pinzi's cross.
Two minutes into injury-time, Luciano pushed Giuseppe Sculli inside the penalty area -- but Stefano Sorrentino saved Floccari's spot-kick.
AC Milan eased early-season pressure on new coach Leonardo as Clarence Seedorf followed up his starring role from the midweek Champions League win over Marseille with the only goal at the San Siro against Bologna.
The Dutch midfielder, who set up both goals for Filippo Inzaghi in the 2-1 win in France, scored the winner in the 75th minute.
AS Roma bounced back from the midweek Europa League defeat by Basel to beat Fiorentina 3-1 in the late match and move away from the relegation zone.
Captain Francesco Totti scored the opener from the penalty spot in the 27th minute and doubled the lead six minute later, then Italy midfielder Daniele De Rossi made it 3-0 four minutes before halftime.
Fiorentina, who had been seeking to overtake Genoa and claim fourth place, scored an 84th-minute consolation through striker Alberto Gilardino.
In Sunday's other games, Parma beat Palermo 1-0 to join Milan on seven points, Catania drew 1-1 at home to Lazio to pick up their first point this season, while bottom side Atalanta suffered a fourth successive defeat, 4-1 at Bari.