Inter Milan pulled clear at the top of Serie A after coming from behind to beat Bologna 3-1 on Saturday, while Roma dispatched Genoa to jump into second and Napoli's torrid start continued with a shock defeat by Venezia.
The champions moved up to 19 points, although Lazio can go level with the leaders if they beat Juventus in Turin on Sunday.
A 2-0 win for Roma at the Stadio Olimpico moved them two points off top in second, while Napoli's loss left them a distant ninth, nine points off the title pace.
Inter came in for criticism after a disappointing midweek Champions League defeat against Club Brugge but bounced back with a comeback win ahead of the visit of Shakhtar Donetsk on Wednesday.
"Our strength is the group and the quality of the players," Inter assistant coach Aleksandar Kolarov told DAZN.
"We don't have anything to prove to anyone except ourselves. We want to be more intense with and without the ball."
Bologna started brightly as Tommaso Pobega fired them in front after 10 minutes before hitting the bar with a powerful shot.
But Inter, shorn of injured captain Lautaro Martinez after he was ruled out for a month, responded through a towering Marcus Thuram header.
Chivu's substitutions proved decisive as Carlos Augusto scored within a minute of coming on midway through the second half, before turning provider for fellow replacement Ange-Yoan Bonny late on.
Just three days after throwing away a 3-1 lead to lose 4-3 in the dying minutes of a Champions League clash with Real Madrid, Roma responded strongly with a 2-0 win over Genoa.
With top scorer Donyell Malen suspended and several key players injured, Roma's young guns seized their chance as Santiago Castro and Emanuele Lulli scored their first goals for the club.
Both sides were denied by the woodwork in the first half, but an audacious flicked finish in a crowded box from Castro broke the deadlock after 50 minutes, before teenage wing-back Lulli made sure of the points with a close-range effort.
Genoa coach Daniele De Rossi, a celebrated former Roma player and coach, received a warm ovation from the home support but was unable to prevent counterpart Gian Piero Gasperini from claiming the 300th Serie A win of his managerial career.
Venezia coach Davide Nicola masterminded a shock 1-0 win over struggling Napoli on debut as Kevin De Bruyne had a penalty saved.
Renowned survival specialist Nicola was appointed during the week to replace sacked coach Giovanni Stroppa after last season's Serie B champions failed to pick up a single point in their opening six games.
He made an instant impact as Akor Adams struck the winner early in the second half to seal Venezia's first Serie A win over Napoli since 1942.
Rested Napoli stars Rasmus Hojlund and De Bruyne came on as coach Massimiliano Allegri searched for an equaliser and Hojlund soon won a penalty, but the Belgian midfielder's spot-kick was saved by Filip Stankovic.
The Venezia goalkeeper proved decisive in the closing stages with a string of impressive saves as Napoli pushed forward in vain.
It marked a second defeat in a row for Allegri's side after their midweek Champions League loss at Villarreal, and the first time in 25 years that Napoli have lost five of their first nine games in all competitions.
Next up for Napoli is the visit of Bodo/Glimt in the Champions League on Tuesday.
"In football you get moments like this and there is only one way out: keep working seriously and professionally, be more focused and turn this disappointment into anger," Allegri told a press conference.
"It's up to us to turn this situation around, starting with the Champions League."
Napoli are ninth on 10 points, while Venezia remain bottom with three points.