The boot was on the other foot this time as they came from behind twice in the closing stages to snatch a second successive home win.
Southend looked on course for a hat-trick of wins after their slow start to the campaign when Alan McCormack gave them a deserved first- half lead.
His low volley from outside the area was not cleanly struck but still found the net through a ruck of bodies.
The Shrimpers were still leading deep into the second half when Brighton boss Dean Wilkins made a series of substitutions which turned the match.
Bas Savage and Sam Rents both came on to play a big part in Brighton's improbable triumph.
With virtually his first touch in the 75th minute, Savage headed a cross from Rents goalwards for Nicky Forster to knock in his first goal for the club since his summer move from Hull.
Southend regained the lead three minutes later when captain Kevin Maher chipped into the box for Nicky Bailey to volley in from eight yards.
The home team were back on terms five minutes from time as Savage crossed for his former Reading team-mate Forster to head into the roof of the net.
The unmarked Dean Hammond completed a remarkable turnaround when he headed in a Rents corner at the far post in the first minute of stoppage time.
George O'Callaghan, signed on-loan from Ipswich until January, was influential in midfield on his Brighton debut, despite being forced to leave the pitch in the first half to have three stitches in a cheek wound.
The Seagulls also gave a debut to French loan signing David Martot from Le Havre on the right side of midfield, but it was his replacement, Savage, who made the difference.
Southend looked on course for a hat-trick of wins after their slow start to the campaign when Alan McCormack gave them a deserved first- half lead.
His low volley from outside the area was not cleanly struck but still found the net through a ruck of bodies.
The Shrimpers were still leading deep into the second half when Brighton boss Dean Wilkins made a series of substitutions which turned the match.
Bas Savage and Sam Rents both came on to play a big part in Brighton's improbable triumph.
With virtually his first touch in the 75th minute, Savage headed a cross from Rents goalwards for Nicky Forster to knock in his first goal for the club since his summer move from Hull.
Southend regained the lead three minutes later when captain Kevin Maher chipped into the box for Nicky Bailey to volley in from eight yards.
The home team were back on terms five minutes from time as Savage crossed for his former Reading team-mate Forster to head into the roof of the net.
The unmarked Dean Hammond completed a remarkable turnaround when he headed in a Rents corner at the far post in the first minute of stoppage time.
George O'Callaghan, signed on-loan from Ipswich until January, was influential in midfield on his Brighton debut, despite being forced to leave the pitch in the first half to have three stitches in a cheek wound.
The Seagulls also gave a debut to French loan signing David Martot from Le Havre on the right side of midfield, but it was his replacement, Savage, who made the difference.