Brighton extended their superb start to the Premier League season with a 5-2 victory that left bottom of the table Leicester in turmoil, while leaders Arsenal prepared for the latest test of their flying start at Manchester United later on Sunday.
Graham Potter's fourth placed side made it four wins from their first six games thanks to a second half surge at the Amex Stadium.
Kelechi Iheanacho put Leicester ahead in the first minute, but a Luke Thomas own goal and Moises Caicedo's strike gave Brighton the advantage.
Patson Daka equalised for Leicester, but the struggling visitors collapsed after half-time as Leandro Trossard put Brighton in front before Alexis Mac Allister's double sealed the rout.
Leicester have taken just one point from their first six games, losing five in a row to leave boss Brendan Rodgers under severe pressure.
In a damning assessment of Leicester's predicament, Rodgers admitted after Thursday's defeat against Manchester United that the Foxes, who twice narrowly failed to qualify for the Champions League under his leadership, are not the same club they were two years ago.
Rodgers, who led Leicester to their first ever FA Cup triumph in 2021, also publicly aired his frustration at a lack of backing from the club's owners in the transfer market, with Wout Faes the only outfield player signed since the end of last season.
Rodgers hopes the transfer window closing will refocus an unsettled squad that lost key defender Wesley Fofana to Chelsea, while James Maddison and Youri Tielemans missed out on moves.
But there was no sign of any improvement as Leicester slumped to another dismal defeat in the south-coast sunshine.
Rodgers responded to Leicester's woes by dropping star striker Jamie Vardy and recalling Zambia striker Daka.
The gamble paid off inside 60 seconds as Daka raced onto Harvey Barnes' pass and sent over a low cross that allowed Iheanacho to tap into the empty net.
But Leicester's lead lasted just nine minutes as Trossard picked out Solly March at the back post for a header that deflected in off the unlucky Thomas.
- Leicester misery -
Leicester's insecurities came rushing back to the surface after that blow and they were breached again in the 15th minute.
Maddison conceded possession close to the halfway line, allowing Enock Mwepu to stride forward and slip in Caicedo, who finished emphatically into the bottom corner.
Daka dragged Rodgers' men level out of the blue in the 33rd minute.
Brighton defender Adam Webster gave away possession and, after Lewis Dunk was caught out by Tielemans' lofted pass, Daka ran through to slot past Robert Sanchez.
Albion remained the dominant force and Trossard scored their third from a Pascal Gross pass in the 64th minute.
Mac Allister killed off Leicester, converting a 71st minute penalty after Wilfred Ndidi fouled Trossard, then curling a free-kick past Danny Ward in the final seconds.
At Old Trafford, Arsenal can make it six successive wins as Mikel Arteta's team try to maintain their blistering start.
United represent the first proper test of Arsenal's unexpectedly strong opening.
Starting his reign with two consecutive losses was a humbling experience for United manager Erik ten Hag.
But since then United have won three on the spin, starting with an impressive success over Liverpool before victories at Southampton and Leicester.
United will give Antony his debut after signing the Brazil forward from Ten Hag's former club Ajax in an £82 million deal this week.