Neal Maupay’s first-half effort was enough to sink Leeds 1-0 and clinch Brighton their first Premier League win since November.
Maupay tapped home at the far post for his seventh goal of the season in the 17th minute as the Seagulls halted a 10-game winless run in all competitions.
It was a successful return to Elland Road for Brighton’s Ben White, who helped Leeds win promotion during a loan spell last season, while his former club slipped to a third straight defeat under Marcelo Bielsa for the first time in 12 months.
Bielsa’s side were bidding to bounce back from last week’s embarrassing FA Cup defeat at Crawley.
However, they sorely missed suspended midfielder Kalvin Philiips and rarely got close to producing the form which has won them so many admirers in the top flight.
The Seagulls’ confidence soared and they went close again when Trossard’s cross was deflected on to the crossbar by Ayling.
With half-time approaching, Leeds were struggling to get a grip on the game in the absence of Phillips and, on a heavy pitch, repeated misplaced passes invited Brighton on to the offensive.
The home side stepped up a gear after the restart and Jack Harrison fired just wide after Raphinha had cut in from the left as Leeds showed some rare fluency.
But another error at the back almost undid Leeds’ good work. Alioski’s underhit pass was pounced on by Maupay and he fed Trossard, who was a whisker away from making it 2-0.
He played most of his 46 games for Leeds last season as a centre-half, but was helping Brighton dictate the play from central midfield.