Inter Milan fell further behind leader Juventus after being held 1-1 at home to struggling Genoa.
Inter, nine points behind the defending champion which beat Cagliari 3-1 on Saturday, had to rely on a goal from Argentine veteran Esteban Cambiasso five minutes from time to rescue a point.
Genoa's Ciro Immobile had given the visitor the lead in the 77th minute with an exquisite shot with the outside of his right foot.
Cambiasso headed the leveller after being set up by Italian forward Antonio Cassano.
The host should have stolen all three points in the final minute of normal time but for a remarkable miss by 19-year-old Croatian Marko Livaja, who missed an open goal and hit the post.
The point could ease the pressure on Genoa coach Luigi Delneri, though it remains second from bottom and has taken just five points since he took over on 22 October.
Lazio later leapfrogged Inter into second place, eight points behind Juventus, after edging Genoa's city rival Sampdoria 1-0 with a goal by Brazilian midfielder Hernanes to take its tally to 17 points from their last 21.
Napoli got back to winning ways - after two defeats to Bologna in four days in Serie A and then the Italian Cup - beating bottom side Siena 2-0 with late goals from Christian Maggio, who was set up by Slovakian Marek Hamsik, in the 86th minute and Edinson Cavani who scored his 13th of the season from the penalty spot in the 90th minute.
Juventus needed two goals in stoppage time to seal a come-from-behind 3-1 win at Cagliari on Saturday.
Cagliari, just a point above the relegation zone, went ahead after 16 minutes through a Mauricio Pinilla penalty awarded after Arturo Vidal had chopped down Marco Sau in the box.
In a contentious game, Cagliari played the last 30 minutes a man short after the sending off of Davide Astori, who had already been booked, for a foul on Sebastian Giovinco.
Alessandro Matri, playing against his old club, levelled for Juventus 10 minutes later and added another in the second minute of injury time.
Mirko Vucinic put away the third in the fifth minute of time added on.
"I have waited for this moment for a long time. My morale had gone down because I wasn't scoring but I always believed in myself," said Matri, who hadn't found the back of the net since 29 September.
In the late kick-off, a brace from Erik Lamela inspired Roma to a 4-2 home win over AC Milan at the Stadio Olimpico.
Nicolas Burdisso broke the deadlock in the 13th minute with Pablo Osvaldo doubling Roma's lead 10 minutes later.
Lamela's double ensured there was no way back for the visitor, who at least grabbed late consolation goals through Giampaolo Pazzini and Bojan Krkic after Marquinho was sent off for Roma.