Lazio succeeded in keeping its record free of any defeat, just like Inter, who leads on goal difference (16 points each), achieving its fifth win in six matches.
Gennaro Gattuso's team owes its third consecutive victory to goals from Portuguese Nuno Tavares (3), Dane Gustav Isaksen (23), and Andrea Pinamonti (88), while Georgian Saba Goglichidze (43) scored for Monza, which came despite the expulsion of Lorenzo Lucchesi (35).
Lazio is achieving the best season start in its history, but the Olympic Stadium stands remain almost empty, as the club's Ultras fans have been boycotting the team's home matches since last season due to their sharp disagreement with the president and owner Claudio Lotito.
This victory comes before the capital team faces Juventus next week, in an effort to continue its successful journey this season and compete for the "Serie A" title for the third time in its history and the first in 26 years.
Despite the win, Gattuso angrily criticized his team's performance, saying, "It is unfortunate that we played a first half at this level, then left the initiative to the opponent in the second half and suffered in this way. The situation cannot continue like this; this is not the first time it has happened."
Gattuso, who aspires to regain momentum in his career after failing to qualify for the World Cup with the Italian national team, added, "Competing for the top spots is not our concern at the moment. We have to take things day by day, and commit to our approach based on work and seriousness, and then we will see how far we can go."
Roma returns with minimal damage
In a match where it played more than half an hour with ten men, the other capital team, Roma, was hoping to stay within striking distance of Inter, who won 2-0 against Parma on Saturday, but it remained behind them and behind Lazio by two points (16-14), while Como raised its tally to 11 points.
This is Roma's third draw in its last four matches across all competitions.
The point might be satisfactory for coach Gian Piero Gasperini's team, given that his side played with ten men from the 53rd minute following a direct red card for Dutch striker Donyell Malen after a harsh tackle on Brazilian Kayky.
Despite Como's numerous attempts to open the scoring by exploiting the numerical disadvantage, Roma kept a clean sheet, marking the second-best defense in the league after Cagliari (2).
The team will face a difficult task against host Real Madrid, led by their former coach, Portuguese Jose Mourinho, on Wednesday in the Champions League after a disappointing opening draw in Turkey against Fenerbahçe.
On the other hand, Como, which is participating in the Champions League for the first time, will play away to Dutch side Feyenoord after its big 4-1 win in the first round against Germany's Leipzig.
Roma was close to opening the scoring with a shot from captain Lorenzo Pellegrini from the edge of the penalty area that hit the post (11).
Malen missed a chance before the end of the first half with a shot that hit the side netting from a narrow angle.
After the Dutchman's expulsion, Como sought to exploit the numerical advantage, with Argentine Nico Paz trying a shot over the crossbar.
After that, goalkeeper Pierluigi Gollini saved two attempts from Paz (70 and 77), without coach Cesc Fàbregas's team being able to win despite their dominance.
Cagliari fourth despite its draw
Gasperini said, praising his team's performance, "When you play for thirty minutes with a man down against a team of Como's size, you are satisfied with coming away with a draw."
Milan returned to dropping points with a 1-1 draw away to Sassuolo.
After the Lombard club took the lead through Frenchman Adrien Rabiot, the hosts managed to force a draw through Dutchman Cas Odenthal (68).
Coach Ruben Amorim's team could have taken advantage of Roma's stumble to tie with them in third place, but they remained fourth with 12 points, while Cagliari also failed to advance to third place with a 1-1 draw against Juventus.
Cagliari, which is having a wonderful start to the season, settled for moving up to fourth place at the expense of Milan with 13 points, one point behind third-placed Roma.
Cagliari squandered its lead through Daniel Maldini (20), after Frenchman Randal Kolo Muani equalized the score minutes before the end of the match (81).
In turn, Juventus moved up to sixth place with 11 points.
Bologna achieved its first win in six attempts by beating host Lecce 2-1.
For Bologna, Riccardo Orsolini (17) and Dutchman Jay Idzes (75) scored, while Swedish-Somali Amar Fatah (64) scored for Lecce.