Juventus and Milan, already directly qualified for next season's Champions League, squeezed in narrow victories in midweek to stay in the hunt for a title which will be won by one of the two northern clubs.
With four games remaining, Juve, on 74 points, have a three-point lead on Milan and a 19-point lead on third placed Lazio.
Only one other team will join Juve and Milan in the Champions League in 2012-2013, with the next two places being reserved for the Europa League.
And after Lazio's latest slip-up, their rivals are waiting to pounce.
On Wednesday Lazio spurned the chance to tighten their grip on third place, which offers qualification to Europe's premier club competition via the preliminary rounds, by succumbing to a surprise 2-1 defeat against relegation-threatened Novara.
The absences of Brazilian playmaker Hernanes and Germany striker Miroslav Klose continue to dog Lazio. The only positive for the Biancocelesti ahead of their trip north is the fact Udinese's recent form has left a lot to be desired.
From the five teams sitting below Juve and Milan, it is Inter and Napoli who look to have the momentum.
Inter's exit from the Champions League at the hands of Marseille in the round of 16 six weeks ago was followed by a small lull in the league, which resulted in the sacking of Claudio Ranieri.
His replacement, Andrea Stramaccioni, has since restored a number of veterans to the starting line-up and Inter have been unbeaten for their last five league outings.
Inter's 3-1 away win over Udinese on Wednesday, was marked by a brace from Dutch striker Wesley Sneijder, who ended a six-month goal drought, and gave the visiting fans hope that the Champions League is within reach.
On Sunday Inter host Cesena at the San Siro where anything less than three points will cause uproar among the Nerazzurri fans.
Novara's return to Serie B will be guaranteeed if they are defeated by Juventus, meaning the minnows from the north-western Piedmont region need a win to have any chance of beating the drop.
That task comes with the caveat that Antonio Conte's giants from Turin -- who sent Cesena back to Serie B on Wednesday -- are unbeaten in 2012.
On Saturday, Napoli moved into third place after a 2-2 draw at Roma, but their hopes of making the Champions League next season were left on a knife-edge.
Napoli have 55 points, but will slip back to fourth on Sunday if Lazio avoid defeat against Udinese with three games left to play.
Catania's outside hopes of playing in the Europa League next season suffered a setback when they were held to a 1-1 draw by Palermo in the Sicilian derby.
Caligari match against Chievo also ended in a draw, 0-0.
Fixtures (all times GMT):
Sunday: Bologna v Genoa (1030), Atalanta v Fiorentina, Inter Milan v Cesena, Lecce v Parma, Novara v Juventus, Siena v AC Milan (all 1300), Udinese v Lazio (1845)
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