Inter Milan laid down an early title marker on Saturday by handing out a 5-1 derby hammering to AC Milan and going it alone at the Serie A summit.
Four wins from their opening four matches have Inter leading the pack with a perfect 12 points, two ahead of their other fierce rivals Juventus who earlier beat Lazio 3-1.
Milan are third, a further point back after being taught a humiliating lesson by their local rivals.
Spurred on by the majority of a heaving and raucous San Siro crowd, Inter claimed their fifth straight derby win in all competitions thanks to a Henrikh Mkhitaryan brace, Marcus Thuram's rocket and two late strikes from Hakan Calhanoglu and Davide Frattesi.
Simone Inzaghi's side claimed the points with a display which showed why they got past Milan to reach last season's Champions League final and confirmed their status as early title favourites.
Thuram also continued his fast start in an Inter shirt, the new man also crucial to Mkhitaryan's fifth-minute opener.
France forward Thuram bundled past Malick Thiaw before finding Federico Dimarco whose mishit shot was guided home by the former Armenia midfielder, who almost headed in a second six minutes later.
And Thuram then underlined Inter's superiority seven minutes before the break after a lightning breakaway started by Lautaro Martinez, collecting from Denzel Dumfries before cutting inside the hapless Thiaw and crashing in an unstoppable shot from the edge of the area.
The match looked dead and buried with 45 minutes to play but Rafael Leao halved the deficit in the 57th minute when he rolled in his second of the season after being brilliantly put through by Olivier Giroud.
Milan's loud "away" support urged their team on, but Mkhitaryan silenced them with his deflected second of the evening after being fed by Martinez.
Former Milan man Calhanoglu's 79th-minute penalty and a neat stoppage-time finish from Frattesi rubbed salt into the wounds.
Vlahovic at the double
Goals in each half from Vlahovic and another in the 26th minute from strike partner Federico Chiesa at the Allianz Stadium briefly pushed Juve top of the pile before Inter's derby delight.
Massimiliano Allegri's Juve were going to concede top spot whatever the result at the San Siro but the coach will be encouraged by what he saw in front of an enthusiastic home crowd in Turin.
Allegri has paired Vlahovic and Italy star Chiesa up front this season and the attacking duo have hit it off, combining for seven goals in unbeaten Juve's opening four matches.
Vlahovic has scored four times after a tumultuous summer dominated by rumours that he might be sold and replaced by Romelu Lukaku, now on loan from Chelsea at Roma.
Chiesa, who missed Italy's two recent Euro 2024 qualifiers with a muscle problem, has started the domestic season in great form after struggling with injuries in recent years.
"We're really good friends, we've known each other a long time," said Vlahovic of Chiesa, with whom he also played at Fiorentina.
"We're really happy to have him fit and healthy."
Lazio, who scored through a beautiful 64th-minute Luis Alberto curler, just before Vlahovic netted his second, are 15th following their third defeat of the season.
Juve's win was a positive end to a difficult week in which star midfielder Paul Pogba was suspended for a doping violation and Italy defender Leonardo Bonucci announced legal action for what he called "humiliating" treatment by his former club.
Champions Napoli are at Genoa in Saturday's late match, trying to get back on track after falling to home defeat at the hands of Lazio last time out.