Trossard's goal was his first since the opening day of the season against Chelsea. It was a clever finish from the Belgian international and capped a fine flowing move from Brighton after good build up play from Pascal Gross and Alexis Mac Allister.
Tottenham, who were without their key striker Harry Kane who injured his ankle in midweek against Liverpool, lacked a cutting edge and energy.
Brighton fully deserved their victory and should have added a second at the end when Aaron Connolly, on as a second half sub, saw his effort from three yards blocked by Alderweireld.
Scroll down and click through to see ho the Albion players rated.
1. Sanchez 7/10
A super save to deny Carlos Vinicius in the second half. Another solid display from the Spaniard. Didn't have an awful lot of work as Brighton dominated possession and were defensively sound but concentration levels remained high
2. Ben White 7/10
Another very composed and classy display from the Brighton defender. Dealt well with Steven Bergwijn and joined the attacks when he could.
3. Lewis Dunk 7/10
The leader of Brighton's impressive backline. Defended and blocked well he needed to and always composed and good in possession
4. Adam Webster 7/10
Another strong display and every inch a Premier League defender. Kept Gareth Bale pretty quiet throughout and provided a defensively solidity. Moved forward well with the ball and helped to start attacks