Brighton's superb start to the Premier League season continued as they held off a late Leicester rally to move up to third place in the table.
The Foxes twice thought they had rescued a point in the closing stages but Ademola Lookman and Wilfred Ndidi both saw goals chalked off for Harvey Barnes straying offside.
Brighton bossed the opening hour but needed a controversial penalty to set them on their way, Neal Maupay scoring his third goal of the season from the spot after Jannik Vestergaard's handball.
Vestergaard argued a foul by Maupay led him to handle Shane Duffy's header but, after lengthy deliberations, referee Stuart Attwell awarded a spot-kick.
Danny Welbeck doubled Brighton's advantage early in the second period, glancing home a near-post header from Leandro Trossard's free-kick out wide.
Leicester finally sprang into life, Jamie Vardy halving the deficit by side-footing Youri Tielemans' first-time cross in from close range after a fine one-touch move.
But they were denied a point as Barnes was twice adjudged to have interfered with play when Lookman scuffed home from a corner and Ndidi headed in from another.
Defeat marked a third loss in five games for Leicester while Brighton registered their first Premier League victory over the Foxes in nine attempts since their promotion into the top flight four years ago.