Phil Foden became the 10th player to score 50 Premier League goals for Manchester City with his first strike at the Amex
What threatened to be a dangerous fixture was effectively over by the interval as City romped into a three-goal lead, moving ahead of Liverpool into second place and closing ominously on Arsenal.
Kevin de Bruyne's first header in his 68 Premier League goals, a magnificent flying effort into the top corner, set City on their way before Phil Foden controversially doubled the advantage nine minutes layer.
Referee Jarred Gillett awarded City a free-kick despite Foden only appearing to slip, Brighton seeing insult added to injury as his resulting set-piece strike took a deflection off Pascal Gross to wrong-foot keeper Jason Steele.
Any hope of a Brighton comeback was extinguished after 34 minutes by a smooth Foden finish into the bottom corner, after the Seagulls had been caught in possession trying to play out from the back.
It was then simply a case of damage limitation for Roberto de Zerbi's side but City extended their lead just after the hour when the ball ran away from Steele as he went into a challenge with Kyle Walker and Julian Alvarez was on hand to pounce.
-- Courtesy of BBC Sport