Lazio moved level on points with Inter Milan at the top of Serie A with a 3-1 win over Monza on Sunday as pursuers Roma and AC Milan were both held.
Ten-man Roma could not keep pace as Donyell Malen's red card overshadowed a 0-0 stalemate in Como to sit two points behind with leaders in third.
AC Milan were held 1-1 at Sassuolo to leave them four points adrift of the leaders in fourth.
Under Gennaro Gattuso, who has bounced back after his failure at the helm of the Italian national side who missed out on the 2026 World Cup, Lazio continued their strong start to the season.
Still unbeaten, the Roman outfit secured a fifth victory in six matches to pull level on 16 points with Inter Milan, who beat Parma 3–0 at the San Siro on Saturday.
"We can't look at the standings, otherwise we will get dizzy. We have to take it day by day," said Gattuso.
Their run comes despite ongoing fan protests against owner Claudio Lotito that have left Lazio's home matches sparsely attended amid a stadium boycott.
Nuno Tavares gave Lazio a third-minute lead and Gustav Isaksen doubled it midway through the first half.
Monza had Lorenzo Lucchesi sent off on 35 minutes for hauling down Tijjani Noslin as he broke through on goal, but the 16th-placed visitors rattled Lazio after the break, pulling a goal back and coming close to equalising before conceding a third goal in the closing stages.
Ruben Amorim's Milan maintained their unbeaten start but drew for the third time in their last four league games.
Matteo Gabbia went off injured early on with the breakthrough not coming until the 63rd minute when Luka Modric slipped in Adrien Rabiot to fire home a powerful finish.
Sassuolo responded immediately as Mike Maignan was forced into a double save, and the Rossoneri's lead lasted just five minutes before substitute Cas Odenthal turned in the equaliser in a crowded box from a corner.
- Malen's costly red card --
Roma continued their unbeaten start against Como but could only pick up a point in the first goalless draw of the Serie A season.
The dismissal of league top scorer Malen for a dangerous tackle early in the second half forced Roma to scale back their ambitions after a bright start.
Neither team could find the breakthrough in a clash between two sides widely regarded as dark horses for the title.
"We played two thirds of the match a man down, that is the disappointing thing," Roma coach Gian Piero Gasperini told DAZN.
"We were confident we had an excellent chance, but we were forced to defend with 10 men, and we did so with order and clarity. When you play 30 minutes with 10 men and come away with a draw, that is fine."
Roma had the better of the first half as Lorenzo Pellegrini, making his first league start in six months, curled a shot off the post after Paulo Dybala's weak finish failed to trouble Jean Butez.
But Malen's reckless lunge eight minutes into the second half proved costly as the Roma striker, who has scored six league goals this season, was shown a straight red card.
Como were unable to find a way past Pierluigi Gollini as the Roma goalkeeper kept a clean sheet on his first league appearance for more than two years following an injury to first-choice Mile Svilar.
Both sides are in Champions League action on Wednesday, when Roma host Real Madrid at the Stadio Olimpico and Como travel to Feyenoord.
Bologna picked up their first win of the season by beating Lecce 2-1.
Surprise package Cagliari welcome Juventus to the Unipol Domus in the late kick-off on Sunday.