Notts County stumbled to their fifth home defeat of the season as Brighton stormed back to form after their 4-1 mauling by Bristol City a week ago.
Notts started the game brightly but their inability to extend a strong Seagulls rearguard was to prove their undoing.
Never in the remainder of the contest were Notts as impressive as in those first 15 minutes, after which Brighton's deadly marksman Leon Knight edged the visitors in front.
Kerry Mayo did the hard work with a good cross, which Knight converted.
Notts struggled to get back into it but were offered a lifeline when awarded a penalty for a tug on Paul Riley's shirt.
With penalty expert Mark Stallard relegated to the bench the kick was left to Paul Heffernan, who drove the ball firmly past Ben Roberts.
But it was Brighton who went back in front again on 37 minutes - again thanks to Knight, his 15th goal of the season.
Steve Mildenhall touched the ball away and Knight, completely unmarked, flashed it into the back of the net.
Notts were unlucky when Ian Baraclough struck a 20-yard volley against the angle of the woodwork and in the second half defender Danny Livesey, moving up into attack, also hit a post.
Otherwise the best Notts chance of an equaliser fell to Heffernan after a rare mix up in the Brighton defence, but he lifted the ball wide of the empty net.
Brighton had five players cautioned and on 86 minutes a heavy challenge by John Piercy on Ian Richardson led to his dismissal - only a minute after his first caution.
But Brighton continued to hold firm with Danny Cullip and Guy Butters outstanding at the back.
Knight continued to be a menace throughout and had three chances of completing his hat-trick as his sheer pace often carried him away from toiling defenders.