The winger, on loan from Manchester United, scored from the halfway line just before the break but relegation-haunted Brighton have now lost four on the trot.
The result was tough on the South Coast strugglers though. They had been the better side in the first half after been forced into a late reshuffle. Richard Carpenter suffered a calf injury in the warm-up and had to be replaced by Colin Kazim-Richards.
Sebastien Carole should have put Brighton ahead in the ninth minute. A cross from fellow Frenchman Alexandre Frutos found Carole in space but the winger saw his shot blocked by Alec Chamberlain.
Carole, returning from an ankle injury, hit the bar from 20 yards out midway through the first half.
The 41-year-old Alec Chamberlain, deputising in goal for Watford for the banned Ben Foster, then parried a fierce drive from Kazim-Richards after the young striker had robbed Jordan Stewart.
Eagles stunned the home supporters with a killer blow in the final minute of the first half.
Brighton keeper Wayne Henderson raced out of his area to head clear as Watford marksman Marlon King chased a long pass. The ball fell to Eagles a couple of yards inside the Brighton half and he found the vacant net with a sweet right-foot shot over the retreating Henderson and a couple of defenders.
Brighton could not find a way through in the second half and Henderson kept them in contention with saves from King (twice), and substitute James Chambers.
The home side came closest to an equaliser deep into stoppage time, Gary Hart heading over from Frutos' free-kick.
The result was tough on the South Coast strugglers though. They had been the better side in the first half after been forced into a late reshuffle. Richard Carpenter suffered a calf injury in the warm-up and had to be replaced by Colin Kazim-Richards.
Sebastien Carole should have put Brighton ahead in the ninth minute. A cross from fellow Frenchman Alexandre Frutos found Carole in space but the winger saw his shot blocked by Alec Chamberlain.
Carole, returning from an ankle injury, hit the bar from 20 yards out midway through the first half.
The 41-year-old Alec Chamberlain, deputising in goal for Watford for the banned Ben Foster, then parried a fierce drive from Kazim-Richards after the young striker had robbed Jordan Stewart.
Eagles stunned the home supporters with a killer blow in the final minute of the first half.
Brighton keeper Wayne Henderson raced out of his area to head clear as Watford marksman Marlon King chased a long pass. The ball fell to Eagles a couple of yards inside the Brighton half and he found the vacant net with a sweet right-foot shot over the retreating Henderson and a couple of defenders.
Brighton could not find a way through in the second half and Henderson kept them in contention with saves from King (twice), and substitute James Chambers.
The home side came closest to an equaliser deep into stoppage time, Gary Hart heading over from Frutos' free-kick.