Sampdoria sank champions Inter 1-0 with a second-half Giampaolo Pazzini goal to go top of Serie A yesterday.
The forward side-footed in a Daniele Mannini cross in the 72nd minute after a slip-up by Inter full-back Davide Santon to give the Genoa side a home win and 15 points from six games.
Inter, who are two points behind in second spot, came close with a powerful Samuel Eto'o shot shortly before Pazzini struck, but the champions could have few complaints as they rarely had the Samp backline at full stretch.
Juventus, who also have 13 points, will go solo at the summit if they beat Bologna at home today.
"It was a very important goal in front of this full house," Pazzini told Sky television.
"We're top. It's a great night."
"We picked ourselves up immediately after Florence," he added, referring to Wednesday's 2-0 defeat at Fiorentina that ended a run of four wins.
Samp midfielder Angelo Palombo fluffed the best chance of an intense first half after an Antonio Cassano cross created mayhem in the middle of the Inter box.
Cassano, snubbed by Inter when they were searching for a playmaker in the close season, also had a good opportunity in the 39th minute but bizarrely he went to ground instead of going for goal having skipped past Lucio, getting himself booked.
Inter substitute Ricardo Quaresma had an equaliser disallowed for offside and Samp keeper Luca Castellazzi produced a fine save to keep out a Lucio free-kick in injury time.
In the late kick-off, Fiorentina, put aside the turmoil caused by president Andrea Della Valle who resigned last week, when they beat struggling Tuscan rivals Livorno 1-0.
Fiorentina's winner came from a second-half penalty scored by substitute Stevan Jovetic following a foul on Alberto Gilardino inside the opponents' box.
Mourinho ends silence
Coach Jose Mourinho ended a six-day media boycott last night but made it clear he was doing so begrudgingly.
The Portuguese had skipped news conferences and interviews after being sent to the stands in Inter's 2-1 win at Cagliari last weekend.
"I'm not continuing the silence because the club asked me because of contracts with you," Mourinho told Sky television.
"If it were up to me the silence would continue."
The former Porto and Chelsea boss, who returned to the dugout after being suspended for Wednesday's 3-1 win over Napoli, would not give a reason for the blackout.
However he has frequently complained about the grilling he is subjected to during post-match interviews in Italy.
Mourinho gave curt responses to several questions.
When asked about the formation he used, he replied: "I'm the coach. I decide and I don't have to explain."
In one of the few full answers he gave, Mourinho blamed injuries for the 1-0 upset to Sampdoria.
"A team that loses (Thiago) Motta and (Wesley) Sneijder loses something in midfield," he said.
Next Fixtures
Playing today - 15.00
Catania vs Roma
Chievo vs Atalanta
Juventus vs Bologna
Lazio vs Palermo
Milan vs Bari 20.45
Napoli vs Siena
Parma vs Cagliari
Udinese vs Genoa
Tomorrow
Ancona vs Modena 19.00
Reggina vs Piacenza 21.00
Saturday
Bari vs Catania 18.00
Inter vs Udinese 20.45
Sunday - 15.00
Atalanta vs Milan
Bologna vs Genoa
Cagliari vs Chievo
Fiorentina vs Lazio
Palermo vs Juventus 20.45
Roma vs Napoli
Sampdoria vs Parma
Siena vs Livorno