Tottenham dropped three points in the race for fourth place after failing to trouble Brighton with a shot on target before Leandro Trossard struck a 90th-minute winner.
The first-half passed by largely without incident down the Brighton end, the visitors having shocked Arsenal just a week ago and fancying the same with a Joel Veltman shot from close-range requiring an urgent Harry Kane block.
Dejan Kulusevski was fortunate to avoid a red card for elbowing Marc Cucurella after receiving a bump from the Spanish wing-back, which earned a rake down his Achilles later on in the half in reply.
In turn, Enock Mwepu was given the benefit of the doubt from Craig Pawson after two risky challenges on a booking.
After the break, Son Heung-min enjoyed little space from good positions in the area as he found blocks denying two goalbound opportunities before Emerson Royal rushed in to deny Moises Caicedo after the ball dropped for the Ecuadorian in the box.
For each spell of Tottenham pressure, Brighton successfully slowed the play down as shown by Caicedo taking his time coming off injured shortly after Pierre-Emile Hojbjerg’s bustling run down the right almost produced a cross to Sergio Reguilon in a great position on 75 minutes.
In the end, it was the away team looking most likely to snatch a winner and, just as a week ago, they upset the team sitting in fourth place when Leandro Trossard beat Eric Dier with a neat piece of skill before poking past Hugo Lloris in the 90th minute.
