On Simone Inzaghi's return to the Stadio Olimpico, his Inter side suffered their first loss of the Serie A season, giving up the lead to lose 3-1 on Saturday evening.
Nicolo Barella continued his prolific start as a provider to the season, darting into the box to manufacture a penalty that Ivan Perisic converted to give Inter a 12th-minute lead.
Maurizio Sarri's Lazio enjoyed lengthy spells of possession, often in Inter territory, but were largely held at arm's length in the first half. The visitors contently shuffled into a compact 5-3-2 off the ball, poised to strike on a counter that never materialised.
Felipe Anderson offered a unique threat for the hosts, at the heart of Inter's greatest cause for concern with his wriggling weaves down the flanks. Darting down the right hand side, Anderson fired a pass into the box which Toma Basic thumped on target but straight at Samir Handanovic in the 24th minute for Lazio's clearest sight of goal.
Lazio continued to toil in vain from open play after the break but were handed a lifeline - quite literally - when Patric headed a corner onto Alessandro Bastoni's outstretched arm shortly after the hour mark. Ciro Immobile sent Handanovic the wrong way to level the match.
As the game threatened to meander to a stalemate, the contest erupted in the final ten minutes. Inter's Federico Dimarco sunk to the turf while his side constructed an attack that broke down and opened up rare space for Anderson to speed into. Lazio's chief threat teed up Immobile for a shot that Handanovic parried to Anderson's feet who tapped to haul the hosts ahead.
Despite the indignant and boisterous protestations of those in blue and black, the goal rightly stood. Sergej Milinkovic-Savic - who admitted pre-game it would be 'strange' to face his former coach - confirmed Inter's late implosion with a header in stoppage time.
Lazio player ratings
1. Goalkeeper & defenders
Pepe Reina (GK) - 6/10 - Beaten from 12 yards but pawed away Perisic's ripper from further out.
Adam Marusic (RB) - 5/10 - Didn't misplace a pass in the first half but that only highlighted his lack of ambition with the ball at his feet.
Luiz Felipe (CB) - 6/10 - Kept Italy's top scorers decidedly short of chances, particularly in open play.
Patric (CB) - 5/10 - Filling in for the suspended defensive lynchpin Francesco Acerbi, Patric did ok.
Elseid Hysaj (LB) - 4/10 - May well be aggrieved by the penalty decision but is experienced enough (200-plus Serie A appearances) to avoid any clumsy contact.
Sergej Milinkovic-Savic (CM) - 7/10 - With his fifth goal in six Serie A meetings with Inter, Lazio's vertically blessed midfielder predictably punished his former coach.
Lucas Leiva (CM) - 5/10 - Quietly anchoring Lazio's midfield three though did a better job of stifling Inter's attacks than launching any for his side.
Toma Basic (CM) - 6/10 - On his first start for the club Basic eagerly charged forward to bolster the attack but squandered a very good chance.
Felipe Anderson (RW) - 8/10 - The main man behind Lazio's most dangerous moves in the first half before putting them ahead in the second.
Ciro Immobile (ST) - 7/10 - Scarcely involved before crisply converting from the spot to score his 100th career goal in the Stadio Olimpico.
Pedro (LW) - 5/10 - Regularly swapping flanks with Anderson but failing to mirror his teammate's threat.
Luis Alberto (CM) - 6/10 - Surprisingly on the bench, but put in a good shift when he came on.
Manuel Lazzari (RB) - 7/10 - Added some much needed thrust to Lazio's play with his searing pace.
Mattia Zaccagni (LW) - N/A
Danilo Cataldi (CM) - N/A
Inter player ratings
5. Goalkeeper & defenders
Samir Handanovic (GK) - 5/10 - Made a crucial save with Inter only narrowly ahead, but gifted Anderson a clear sight of goal later on.
Milan Skriniar (CB) - 7/10 - Never more than a stride or two away from the opponent unfortunate enough to be targeted by the Slovenian.
Stefan de Vrij (CB) - 7/10 - Expertly marshalling Inter's defensive system until their late implosion.
Alessandro Bastoni (CB) - 5/10 - Had looked composed in and out of possession before giving away the equalising penalty.
6. Midfielders & wingbacks
Matteo Darmian (RWB) - 7/10 - Dovetailed menacingly with Barella in a partnership that created the penalty before swung onto the opposite flank.
Nicolo Barella (CM) - 7/10 - Won't be awarded a sixth assist of the season for his penalty win but certainly maintained his superb individual start to the campaign.
Marcelo Brozovic (CM) - 7/10 - Dropping deep to aid in the orchestration of Inter's moves. Another solid performance from the Croatian.
Roberto Gagliardini (CM) - 4/10 - Starting his first league game of the campaign, Gagliardini failed to exert any influence on proceedings.
Federico Dimarco (LWB) - 5/10 - Too often wasted the great swathes of space Inter's choreographed build up painstakingly provided him with.
Ivan Perisic (ST) - 6/10 - Unshackled from his normal wingback role, the ever versatile Croatian international couldn't fully exploit the additional freedom his position change afforded.
Edin Dzeko (ST) - 4/10 - A constant target for Inter's raft of (attempted) crosses into the box but failed to test Reina when the ball found his forehead.
Matias Vecino (CM) - 5/10
Denzel Dumfries (RWB) - 5/10
Joaquin Correa (ST) - 5/10
Hakan Calhanoglu (CM) - N/A