Napoli missed the chance to close the gap on Serie A leader Juventus as it drew 1-1 at Fiorentina on Sunday.
Meanwhile, Giampaolo Pazzini fired AC Milan above Roma and into sixth place in the table with a well-taken brace in a 2-1 win over Bologna.
Fiorentina took the lead following a terrible blunder from Morgan De Sanctis. The Napoli goalkeeper rushed out of his area to intercept a long pass from Facundo Roncaglia by the halfway line, but completely misjudged the ball which bounced over him and into the goal.
Alberto Aquilani could have won it for Fiorentina in stoppage time but blasted a good chance over the bar.
Napoli, which had a two-point penalty for match-fixing rescinded on Thursday, is level on points with second-placed Lazio, five points behind defending champion Juventus.
Fiorentina remains fifth.
At the San Siro, Pazzini grabbed a double as AC Milan edged Bologna, with his second goal borne of fantastic individual skill and a predatory instinct in front of goal.
Philippe Mexes gave the hosts cause for concern with a careless own goal in the final stages but a rejuvenated Milan side found itself back in the race for Europe.
Also on Sunday, Roma's bid to claim sixth place back from AC Milan failed as the Giallorossi were held to a frustrating 1-1 draw by Inter Milan.
Roma had the better chances to win it but both sides appeared to tire quickly as the game soon fizzled out in the second half.
Elsewhere, Chievo restricted Parma to a frustrating 1-1 draw at the Stadio Marc'Antonio Bentegodi that did nothing to boost either side's ambitions.
Genoa coach Luigi Del Neri was sacked after his relegation-threatened side lost 2-0 at home to Catania.
Bottom club Siena recorded a first league win in seven games when Erjon Bogdani settled a 1-0 victory over Sampdoria, while Pescara lost 2-0 at home to Torino thanks to goals from Mario Santana and Alessio Cerci.
Information from Press Association and The Associated Press was used in this report.