Cagliari turned on the style to hold Inter Milan to a 2-2 draw at the San Siro on Sunday as Fiorentina hammered 10-man Atalanta 4-1 at home to take over third place from Napoli.
After leaders Juventus were held to a scoreless draw at home to Lazio on Saturday Inter had a chance to close the gap on the Serie A champions.
But despite Rodrigo Palacio giving the hosts an early lead, a superb double from striker Marco Sau had the Sardinians in front and it took an own goal from Davide Astori for Inter to pull level.
Inter had several chances to score, notably through Diego Milito, in a lively second half.
But the Argentine striker missed two clear chances from close range and was denied a third time by alert Cagliari 'keeper Michael Agazzi.
In the closing minutes Inter piled on the pressure and were unlucky not to be awarded a penalty when midfielder Walter Gargano was hauled down inside the box.
Cagliari held on and in the end were worthy of a share of the points.
Inter handed Juventus their first defeat in 50 games two weeks ago but came up short in the Nerazzurro derby last week with defeat to Atalanta.
Stramaccioni was also red carded for protesting towards the end of the game.
Inter's first draw in 13 matches left them in second place on 28 points, four adrift of Juventus but one ahead of Fiorentina and Napoli, who were held 2-2 at home by AC Milan on Saturday.
Fiorentina maintained their impressive push up the table under coach Vincenzo Montella with a one-sided win over their visitors from Bergamo.
The hosts took a fifth-minute lead when a freekick whipped in from the left evaded the entire Atalanta defence to land at the feet of Gonzalo Rodriguez, who slammed the ball into the net from close range.
Atalanta levelled just after the half hour when Giacomo Bonaventura slammed the ball home from close in after it had ricocheted around the Fiorentina area.
But Fiorentina regained the lead before the interval when Alberto Aquilani sent a sublime freekick from the edge of the area past static 'keeper Andrea Consigli.
Atalanta were then reduced to 10 when Luca Cigarini hauled down Juan Cuadrado as the Colombian midfielder ran down on goal and Fiorentina made the visitors pay when Aquilani beat Consigli from close range following a corner in first half injury time.
Former Italy striker Luca Toni added a fourth goal with a header four minutes into the second-half to consign Atalanta to their fifth defeat of the season.
Siena 1 (Valiani 81) Pescara 0
Bologna 3 (Gilardino 44, Gabbiadini 44-pen, Diamanti 48-pen) Palermo 0
Catania 2 (Bernardo 51, 85) Chievo 1 (Andreolli 90+3_
Fiorentina 4 (Rodriguez 5, Aquilani 42, 45+2, Toni 49) Atalanta 1 (Bonaventura 32)
Inter Milan 2 (Palacio 10, Astori 82-og) Cagliari 2 (Sau 43, 66)
Udinese 2 (Di Natale 9, Pereyra 50) Parma 2 (Marchionni 46, Palladino 89)
Sampdoria 3 (Poli 16, Bovo 36-og, Icardi 88) Genoa 1 (Immobile 73)