Alessandri Matri, who joined Fiorentina on loan from AC Milan on Wednesday, made an immediate impact by scoring twice in the first half as they overcame their injury-crisis with a 3-0 win at table-propping Catania.
Substitute Hernanes scored a last minute goal to give Lazio a 3-2 win at Udinese after they twice trailed and Parma left it even later in a 2-1 win at Chievo Verona 2-1, courtesy of a stoppage time goal by Alessandro Lucarelli.
Sassuolo, whose sensational 4-3 win over AC Milan last week brought about coach Massimiliano Allegri's sacking, were brought back to earth by Torino who won 2-0, hurling them back into the relegation dogfight. They are joint 16th with Chievo and Bologna.
Allegri's replacement Clarence Seedorf was set to make his debut at home to Hellas Verona in the evening match at San Siro (1945).
Genoa's Luca Antonelli easily out-jumped a static Inter defender to head in from a corner with seven minutes left on another miserable afternoon for Walter Mazzarri's team who have won only one of their last eight league games.
In appalling conditions, with large puddles on the pitch, Genoa goalkeeper Mattia Perin ensured three points with a superb late save from Ruben Botta's header.
It was an especially enjoyable win for Genoa coach Gian Piero Gasperini who had a miserable spell at Inter at the start of the 2011/12 season and suffered the indignity of being sacked after five games in charge.
Gonzalo Higuain equalised with a penalty in the 62nd minute and Jose Callejon fired Napoli ahead with 10 minutes to go after Bologna lost possession.
The hosts had Panagiotis Kone dismissed for a second bookable offence but Napoli relaxed too soon as they left Bianchi unmarked to fire the equaliser in the 90th minute.