A magnificent long-range strike from Federico Dimarco set up Inter Milan for a 2-0 win over Frosinone on Sunday that sent them back top of Serie A ahead of the international break.
Among Inter's title rivals, only Juventus won over the weekend. The pair meet in the next round of matches in Turin.
A gap is opening below the two traditional giants, after AC Milan and Napoli continued to lose ground.
Simone Inzaghi's joyful Inter side have won ten of 12 games and have 31 points, with Massimiliano Allegri's Juventus on 29. AC Milan are third on 23 after letting slip a 2-0 lead over Lecce. Defending champions Napoli have 21 after losing to Empoli.
Such is the confidence at Inter, that Dimarco shot shortly after crossing the halfway-line from the left touchline, his arcing shot dropping under the crossbar and into the Frosinone goal with 'keeper Stefano Turati clutching at air.
Hakan Calhanoglu doubled the lead, converting a spot-kick just after the break.
Earlier, Napoli fell to a shock 1-0 home defeat to Empoli, leaving the defending champions on the verge of sacking new coach Rudi Garcia.
Lazio and Roma slugged out a goalless stalemate in the Rome derby.
Napoli were booed off after Viktor Kovalenko's superb last-minute strike snatched the win for Empoli, leaving the hosts eight points behind leaders Juventus and looking over their shoulder.
No-one from Napoli spoke to the media after yet another poor display on home turf. The club have not won a fixture in Naples since the end of September.
The Gazzetta Dello Sport and Naples-based daily Il Mattino both reported that Napoli owner Aurelio De Laurentiis had already decided to sack Garcia and that the Frenchman will not take training on Wednesday.
De Laurentiis has also called a summit in Rome on Monday to decide on the successor, with Igor Tudor and Fabio Cannavaro among the names cited.
- Garcia in trouble -
Garcia took over from title-winning coach Luciano Spalletti in the summer but his days already look numbered after a poor performance against Empoli who lifted themselves out of the relegation zone.
The 59-year-old Garcia won Ligue 1 with Lille in 2011 but his stock has fallen dramatically since being sacked by Roma in early 2016.
He was fired from Al Nassr in April, after the Saudi Arabian club signed Cristiano Ronaldo.
Napoli's home record is the 15th-best in the league while on the road where they are unbeaten in all competitions and have won six from eight fixtures.
Three defeats in six league home matches is already more than last season's total but didn't lead to them losing their place in Italy's top four.
- Dismal derby -
Lazio and Roma meanwhile played out a goalless draw in a Rome derby which was full of needle between fans, players and coaches.
Roma would have drawn level on 20 points with Atalanta and Fiorentina if they had won the first Rome derby of the season but offered little at the Stadio Olimpico.
Jose Mourinho's team move up one place to seventh, ahead of Bologna on goal difference, while Lazio stay a point behind their local rivals in 10th.
Nominal hosts Lazio came closest to scoring, Luis Alberto smacking the post in the 25th minute, and three minutes later Roma 'keeper Rui Patricio had to be at his best to keep out Alessio Romagnoli's header.
After the restart, the two teams seemed more interested in avoiding defeat and getting in each other's faces than trying for a win.