After Leandro Trossard opened the scoring early in the first half - both Ruben Loftus-Cheek and Trevoh Chalobah scored own goals - leaving Chelsea 3-0 down at half-time.
Potter’s makeshift wing back positions were exploited by his successor Roberto De Zerbi but the Blues changed formation to gain control of the second half.
However, it was too little too late as the Blues were unable to follow up on Kai Havertz’s header early in the first half, losing 4-1 in the process as Pascal Gross sealed victory in stoppage time.
Nizaar Kinsella was at the Amex Stadium to rate the Chelsea players...
Kepa Arrizabalaga - 6
Kepa has been great rushing out recently but could do little as Trossard used his speed and balance to avoid his challenge and score in the fifth minute. Towards the end of the first half, Kepa began to struggle with injury and came off at half-time.
Trevoh Chalobah - 6
Strangely, Chalobah was the least at fault for his own goal. He was simply scrambling to clear a dangerous Pervis Estupinan cross that he simply had to cut out. Unfortunately, luck was not on his side as it squirmed into his own goal. Amid a good run of form, he was probably the best of the defenders once again.
Thiago Silva - 5
Quite an incredible opening to the game, giving the ball away before clearing off his own line from a Trossard lob. He did so again at a corner just a minute later but, eventually, his mistake led to Brighton’s opener as Trossard danced past Kepa after Kaoru Mitoma’s cute pass.
Marc Cucurella - 4
Brighton’s reigning Player of the Year was booed with his every touch upon his return to the south coast. It was an awful afternoon for the £62million signing who was exposed time and again by his old team’s system.
Christian Pulisic - 5
In his first consecutive starts of the season, Pulisic played in a hybrid right wing-back and right wing position. He almost got in during the ninth minute. He defended marginally better than Sterling but both he and Conor Gallagher were at fault for not cutting out Moises Caicedo’s pass for the third goal.
Conor Gallagher - 6
Missed a simple chance from eight yards in the 17th minute, another pivotal moment in the match. His header in the 20th minute was well saved by Sanchez and his brilliant cross set up Havertz’s header early in the second half.
Ruben Loftus-Cheek - 5
Loftus-Cheek scored a terrible own goal - a total unforced error. He simply let the ball hit him at Mitoma’s corner, an inexplicable mistake. Switched to right-back in the second half and was involved in the creation of Havertz’s goal. In fact, he was at his creative best on the right flank but his poor own goal remained a sore point.
Mateo Kovacic - 5
Booked for a high challenge on Solly March in the 11th minute. It was a quiet game for the midfielder who rarely progressed into attacking positions and couldn't control the game as Jorginho did midweek.
Raheem Sterling - 4
Sterling was good going forward and bad whenever Brighton broke the press. He created a huge chance for both Gallagher and then Pulisic in the 16th minute, following it up with a great cross for Gallagher’s header four minutes later. He did well against Adam Webster whenever going one-v-one. It still feels like he unbalances the team though, as Cucurella was left exposed by the space behind Sterling.
Mason Mount - 5
Had Chelsea’s first shot of the game midway through the first half, which sparked a resurgence after going 2-0 down. Fired in a more hopeful effort from distance in the 60th minute, but it went well wide.
Kai Havertz - 7
A great first touch and shot helped keep the pressure on Brighton in the 21st minute. His running in behind also stretched Brighton to relieve pressure. Tucked away his first big chance nicely at the start of the second half and he missed a decent opening in the 86th minute.
Edouard Mendy - 5
Made his 100th appearance for Chelsea, finally, coming on for Kepa. It was his first taste of action under Potter. His poor kick to Mitoma led to a chance for Trossard midway through the second half yet he steadied himself to make several interventions. Unconvincing after being peppered with shots late on to concede Gross' fourth.
Ben Chilwell - 6
Given the encouragement from Potter to go and attack, a logical substitution but the game had already escaped the Blues.
Hakim Ziyech - 7
Almost scored with a dangerous whipped free-kick that had Sanchez worried.
Pierre Emerick Aubameyang - 5
Couldn’t really impact the game after coming on.
Armando Broja - 5
One of three strikers on the pitch in the last 10 minutes, it was all a bit chaotic for him to impact the game.
Unused subs: Azpilicueta, Zakaria, Jorginho, Hutchinson.