Champions Inter recorded their third straight draw when they were held 0-0 by Sampdoria on Saturday after having two players sent off and second-placed Roma took advantage despite showing late nerves.
Montenegro striker Mirko Vucinic, up front alone with Francesco Totti suspended and Luca Toni injured, prodded in an 18th-minute corner to overcome visiting Catania who are fourth from bottom.
Claudio Ranieri's Roma side, who lost for the first time in 21 matches in Thursday's Europa League game at Panathinaikos, have stormed up Serie A after a sticky start and host Inter in late March in one of their 13 remaining games.
Asked if the title race had reopened, Ranieri told Sky TV: "Honestly no. You still can't say it but we move forward. Our mind is on the Europa League campaign. Inter are a great side."
Third-placed AC Milan, seven points behind Inter and with a game in hand at Fiorentina on Wednesday, triumphed 2-0 at Bari thanks to Marco Borriello's stunning volley and an Alexandre Pato goal.
Italy hopeful Borriello produced a trademark acrobatic strike from Ronaldinho's cross just before the break and the Brazilian also helped set up compatriot Pato on 69 minutes.
Returning Milan goalkeeper Christian Abbiati then expertly saved Paulo Barreto's late penalty.
CANDREVA WINNER
Juventus moved up to fourth after a patchy 2-1 victory at Bologna, their third win in a row under Alberto Zaccheroni.
Brazilian playmaker Diego, criticised by fans and media for his poor form, sliced through the Bologna defence on four minutes and slotted home after his first effort was saved.
Fabio Cannavaro was again left on the bench with Juve playing three at the back but their defence was exposed when Antonio Busce bundled in a 50th-minute equaliser after first hitting the post.
Substitute Antonio Candreva settled matters midway through the second half after an excellent pass from Alessandro Del Piero while Felipe Melo had a third goal ruled out for offside.
Bologna almost levelled before Andrea Raggi received a red card late on.
Napoli and Palermo are one point behind Juve after the Naples club were held 0-0 at bottom side Siena and the Sicilians beat coach Delio Rossi's former club Lazio 3-1.
Cagliari are two points further back following a 2-0 victory over Parma while Alberto Gilardino headed the winner in inconsistent Fiorentina's 2-1 comeback victory over third-from-bottom Livorno.
Atalanta were beaten 1-0 by Chievo to stay in the drop zone.
