(CNN) -- Inter Milan were held to a drab goalless draw by Genoa in the San Siro on Sunday to leave them four points clear of arch-rivals AC Milan in Serie A.
It proved a frustrating night for the reigning champions and in particular their coach Jose Mourinho, who was serving the second of a three-match touchline ban.
He fielded a three-strong attack of Mario Balotelli, Goran Pandev and Diego Milito, but they drew blank against a determined visiting side.
Only in the closing minutes did Inter threaten with Maicon, striking substitute Samuel Eto'o and Wesley Sneijder going close.
Inter moved to 59 points, with Milan their nearest challengers after being held goalless by AS Roma on Saturday.
In other action on Sunday, Palermo stepped up their campaign for a Champions League place with a 1-0 win over Livorno.
Fabrizio Miccoli's goal nine minutes from the end took the Sicilians into fourth place in Serie A, two points clear of Juventus,
Palermo beat Juve in Turin last weekend in a match which could prove crucial in the battle for qualification.
Sampdoria are in sixth, a point further back, after a 2-1 home win over Lazio.
The struggling visitors took a seventh-minute lead through Sergio Floccari but goals later in the first half from Stefano Guberti and Giampaolo Pazzini were enough to give Samp the three points.
Napoli continued to slip down the table after a 2-1 defeat at Bologna, with Marcelo Zalayeta and Brazilian Adailton scoring early goals to claim the three points.