Sampdoria and Genoa missed the chance to end the year in third spot as both teams failed to win in the final round of Serie A fixtures before the winter break.
Sampdoria was held to a 2-2 draw at home to Udinese to leave it behind third-place Napoli on goal difference, while Genoa remained a point further back after losing 2-1 at relegation-threatened Torino.
Lazio could move two points ahead of Napoli and Samp if it wins at Inter Milan later.
Earlier, Chievo Verona beat city rival Hellas Verona 1-0 in a heated derby match.
Also, Fiorentina was held to a 1-1 draw by Empoli, while Atalanta fought back from two goals down to draw 3-3 at home to Palermo.
Sampdoria was in confident mood after holding league leader Juventus to a 1-1 draw in Turin last weekend and it took the lead in the 15th minute.
Udinese goalkeeper Orestis Karnezis could only punch clear Angelo Palombo's cross and it went straight to Pedro Obiang, who turned into the empty net.
However, the match turned in four minutes as Alexander Geijo scored his first Serie A goal in his first start to level matters shortly before Danilo was left unmarked to head Udinese in front.
Manolo Gabbiadini headed Lorenzo Di Silvestri's cross into the top right corner on the hour mark in what could have been his last match for Sampdoria before a likely January move to Napoli.
Geijo almost scored a late winner but his header thumped the post.
Udinese was reduced to 10 men two minutes from time when Thomas Heurtaux was sent off following a second yellow card.
Genoa started the day level with Samp and Lazio on 26 points, and last weekend's defeat to Roma was its first league loss in more than two months.
Fiorentina failed to capitalize on the results of those above it as it remained eighth, three points behind Napoli, after an entertaining Tuscan derby.
Chievo snatched victory in the other derby of the day but replays showed Alberto Paloschi was offside as he headed in Ervin Zukanovic's superb cross into the box with nine minutes remaining.
Both sides also had penalty claims turned down.
Nene had gone closest for Verona when he headed a corner just over the crossbar, while Chievo's Ivan Radovanovic almost scored a wonder goal but Verona goalkeeper Francesco Benussi was alert to turn the effort from near the halfway line over his bar.