In a chaotic opening, Leandro Trossard’s calm finish put the home side in front after Thiago Silva – who had already produced two goalline clearances to deny the Seagulls – surrendered possession cheaply in his own half.
Two own goals extended Brighton’s lead before the break, Ruben Loftus-Cheek putting through his own net from a Solly March corner before Trevoh Chalobah slid Pervis Estupinan’s low cross past Kepa Arrizabalaga.
Kai Havertz nodded in Conor Gallagher’s exquisite cross to give the visitors hope two minutes after the interval, but a second-half Chelsea recovery failed to materialise.
Pascal Gross capped a miserable afternoon for Potter and his players with a close-range finish after Edouard Mendy – who had replaced the injured Arrizabalaga at half-time – parried Julio Enciso’s shot into the German’s path..
Blues self-destruct on Potter return
All eyes were on Potter as he took charge of his first game at Amex Stadium since Brighton’s 5-2 victory over Leicester in early September. The 52-year-old was booed by large sections of the home fans as he took his seat in the dugout, and his mood will not have been helped by his team’s defensive horror show on the south coast.
Silva nearly gifted the home side an opener when his attempted cross-field pass was cut out by Moises Caicedo, but the veteran centre-back atoned for his error with a superb goal-line clearance after Trossard had tried to chip Blues goalkeeper Arrizabalaga.
The Brazilian repeated the feat moments later to prevent Estupinan’s powerful strike from crossing the line, but it was his poor pass that allowed Kaoru Mitoma to set up Trossard for the game’s opening goal on five minutes.
The Seagulls’ second and third goals were also entirely self-inflicted from the visitors’ perspective. Loftus-Cheek stuck out a knee to inadvertently steer Gallagher’s flick-on into the net via the crossbar, before Estupinan’s delivery was guided past his own keeper by the somewhat unfortunate Chalobah.
Chelsea did have opportunities of their own – Christian Pulisic firing wide from a promising position and Robert Sanchez tipping Gallagher’s looping header past the post – but Havertz’s header early in the second half failed to spark a revival.
Havertz should have cut the deficit further but he blazed over the crossbar from inside the penalty area. And Gross finished off an incisive Brighton counter-attack late on to rub salt into Chelsea’s wounds.
While Potter will take some solace from his team’s improvement in the second half, the damage was done before half-time.
Lift-off for Brighton under De Zerbi
A run of five games without a win since Potter’s departure did not make pleasant pre-match reading for Seagulls supporters or their new coaching staff, but Chelsea were unable to cope with Brighton’s high pressing in the early stages as De Zerbi’s team threatened to run riot.
Only Glenn Murray and Neal Maupay have scored more Premier League goals for the Seagulls than in-form Trossard, whose early opener – his 25th in the league for the club – made him the first player to score a club’s first five top-flight goals under a new manager.
Had it not been for Silva’s two last-ditch clearances and a close-range Moises Caicedo effort which struck the outside of the post, they could have been even further ahead by half-time.
The jubilant home fans, who had seen their score just once since the 3-3 draw at Anfield earlier this month, were singing “Potter, Potter, what’s the score?” and “You’re getting sacked in the morning” in the direction of their former manager as the teams made their way off the pitch at the interval.
The Seagulls’ second-half display was more measured as Chelsea sought a route back into the game, but De Zerbi’s side never looked like to surrendering their healthy lead – even after Havertz’s strike.