Lazio moved one point clear at the top of Serie A with a 0-0 draw at Napoli and AC Milan stayed within one point of the lead with another scoreless draw at Fiorentina on Saturday.
Earlier, Inter Milan beat Cagliari 2-1 for just its third win of the Italian season, with second-half goals from Thiago Motta and Coutinho.
The victory at the San Siro lifted the Nerazzurri three points clear of the relegation zone, with a game in hand.
Still, Inter is 11 points behind Lazio, which has 22. Milan and Udinese are next with 21 each and Juventus is fourth with 19.
Udinese will have a chance to go top again when it visits Parma on Sunday, while Juventus can draw level with Lazio when it hosts Palermo.
Lazio was missing its injured leading scorer Miroslav Klose. Napoli created more chances but couldn't beat Lazio goalkeeper Federico Marchetti, who made outstanding saves.
Napoli has a decisive match with Manchester City in the Champions League on Tuesday, while Milan hosts European champion Barcelona a day later.
Milan had won five straight and deserved to win another, as the Rossoneri had a goal from Clarence Seedorf waved off for a questionable offside call in the 19th minute.
Milan striker Alexandre Pato returned from a two-month injury layoff and hit the post in the 77th, with Alberto Aquilani and Antonio Nocerino also producing chances for the visitors.
Fiorentina was without its standout playmaker Stevan Jovetic and Delio Rossi made his debut as the Viola manager after replacing Sinisa Mihajlovic.
At the San Siro, Inter hit the crossbar twice before taking the lead in the 54th following a free kick from Ricardo Alvarez. Giampaolo Pazzini flicked the ball on to Thiago Motta, whose goal from the edge of the box was allowed despite appearing offside.
Coutinho was a last-minute starter after usual playmaker Wesley Sneijder reported a muscle problem during the warmup, and the Brazilian took full advantage when he finished off a swift counterattack with a low shot from the edge of the area in the 60th.
Forward Joaquin Larrivey then pulled one back for Cagliari in the 88th by redirecting a pass from the center of the area, as the Sardinian club showed resilience in its first match under new manager Davide Ballardini.
Cagliari goalkeeper Michael Agazzi deflected shots from Pazzini and Mauro Zarate off the crossbar in the 21st and 24th, and Inter midfielder Esteban Cambiasso sent a dangerous header high in the 43rd as the hosts dominated the first half.
''It was very important after the break to get these three points at home,'' said Thiago Motta, who was born in Brazil but represents Italy. ''We were able to have a decent match against a team that's not easy to play against. We've gone through some tough times and now we've got to continue like this.''
On Tuesday, Inter visits Trabzonspor in the Champions League, seeking revenge against the Turkish squad that handed the Nerazzurri a humiliating home defeat in its debut in the top European competition in September.
