But in inflicting the first defeat of the season on Jose Mourinho’s Inter, Sampdoria emphatically cemented their own title credentials, even though they could lose the lead again if Juventus beat Bologna on Sunday.
Although competitive and lively, the first half produced few genuine goalscoring opportunities as two capable teams largely cancelled out each other.
Mourinho had switched his midfield around, bringing in Mario Balotelli and Patrick Vieira while leaving Dejan Stankovic on the bench.
He also preferred young full-back Davide Santon to experienced Romania international Cristian Chivu at left-back — a move that would later prove costly.
Inter enjoyed more of the ball and created the first real chance when Esteban Cambiasso’s pass released Diego Milito in space down the left and he pulled the ball back to his Argentine team-mate who forced a full length save from Luca Castellazzi.
Lithuanian Marius Stankevicius tried his luck from long-range and his swerving shot proved too hot for Inter goalkeeper Julio Cesar to hold, although the Brazilian beat the ball away.
Antonio Cassano was pulling the strings for Sampdoria and after his cross from the left caused panic in the Inter box the ball seemed to be dropping invitingly for Angelo Palombo 15 yards out but the Italy midfielder fluffed his attempted left-foot volley.
The second half began with a flurry of action as Balotelli’s strike from outside the box took a deflection and wrong-footed Castellazzi.
The goalkeeper just managed to get his hands on the ball and pushed it past the lurking Milito.
Up the other end Pazzini turned smartly in the box and swept a shot just wide of the far post.
But the decisive moment came due to a mistake from from Santon who belied his inexperience by trying to play a risky short pass while deep inside his own half.
He gave the ball away to Palombo who teed-up Daniele Mannini for a shot and while he scuffed his effort it fell to the unmarked Pazzini 10 yards out whose hurried and shanked effort left Cesar rooted to the spot.
Inter had the ball in the net six minutes from time through substitute Ricardo Quaresma when his long range effort deflected off fellow sub Chivu and in but the Romanian was standing in an offside position.
Inter piled on the late pressure but Castellazzi beat away a vicious Lucio free-kick and Samuel Eto’o flashed a volley wide as Sampdoria deservedly held on for the victory.