Federico Dimarco scored the only goal as Inter Milan continued their perfect start to the Serie A season with a 1-0 win at basement team Empoli on Sunday.
Simone Inzaghi's side shifted gear after a hard-fought first half to see off a club who fired their coach last week after a seven-goal thrashing by Roma.
Dimarco made the difference with a superb half-volley into the corner six minutes after the break.
France international Marcus Thuram was denied a second by the crossbar on 77 minutes before being replaced by Chilean Alexis Sanchez who made his Serie A return after spending last season at Marseille.
"It's an important victory, it wasn't easy, but it allows us to send a message to the other teams," said Dimarco.
"We had to wait until the second period to gain the upper hand, but we managed this match well, with the right approach," added Inzaghi.
"It's only the fifth round, we know that everything can change quickly in football, but I am satisfied with my players, with their mental attitude."
Inter, the 2021 champions, are the only team not to drop a point so far, and have three more than second-placed rivals AC Milan who beat Verona 1-0 on Saturday.
Juventus are already five points adrift in fourth after a 4-2 defeat at 11th-placed Sassuolo.
Inter next play Sassuolo midweek but without Austrian striker Marko Arnautovic who pulled up with a "serious injury" to his left thigh, the club announced.
Later champions Napoli were held to a goalless draw at Bologna.
That left Napoli seven points behind Inter and coming on the back of a draw and a defeat in the league increases the pressure from fans on new coach Rudi Garcia.
Garcia's side failed to capitalise on their domination, Victor Osimhen hitting the post early on before last season's top scorer in Serie A missed a 72nd-minute penalty.
"The only negative point of the evening was the result. We deserved to win, that's why I'm disappointed, but the team's performance satisfied me," said Garcia.
Osimhen, who has been linked with a move to the Premier League, was substituted later in the game and made his displeasure known to the coach.
Garcia later said he had "spoken to Victor" before defending his striker for missing the penalty.
"A victory is sometimes decided by a centimetre. Missing a penalty happens to everyone, even to the greatest players like Victor," said the coach.
Garcia will be hoping Wednesday's clash with Udinese brings a change of fortune on the domestic scene.
Meanwhile, Jose Mourinho's Roma were held to a 1-1 draw at Torino which left them in 13th place and just two points above the relegation zone.
Romelu Lukaku scored his second goal of the league season in the 68th minute for Roma but Colombian international Duvan Zapata ensured a share of the spoils five minutes from time.
