Matt Sparrow scored twice as Rickie Lambert's sending off proved to be the turning point in Brighton's victory over Championship leaders Southampton.
Lambert was sent off in the 51st minute after an altercation with Adam El-Abd.
Jake Forster-Caskey, on his full debut, put Brighton ahead, slotting home after Kelvin Davis denied Kazenga LuaLua.
Sparrow fired home a stunning 35-yard strike and added another emphatic finish before captain Gordon Greer was dismissed for an off-the-ball incident.
Saints, who went into the game on the back of a first home defeat in more than a year, only stay top of the league on goal difference following West Ham's 1-0 win over Coventry, while Brighton ended their run of four successive defeats without scoring in emphatic style.
The visitors dominated the first half but were outplayed once Lambert, the division's leading goalscorer, was sent off for the first time in his career.
The hosts, missing 10 players through injury and suspension, were instantly spurred on and Saints had goalkeeper Davis to thank after he impressively denied LuaLua.
However, he was beaten moments later as Forster-Caskey netted the rebound after Davis had initially kept out LuaLua's stinging effort.
Sparrow's magnificent goal then added to the hosts' joy and he added another by firing into the top corner from just inside the area after a goalmouth scramble.
Greer's sending off three minutes from time, the fifth red card shown to a Brighton player this season, following an incident with substitute Jonathan Forte, was the only disappointing aspect of the Seagulls' display, but it mattered little.
The Saints could have scored in the first half but Peter Brezovan made a fine save to deny David Connolly and Guly Do Prado somehow blazed over from six yards.
Lallana was also denied a goal when his effort appeared to cross the line, prior to Steve Cook's clearance.
Southampton manager Nigel Adkins:
"The sending off of Lambert was a massive turning point as we were in control of the match at that time. It changed the whole complexion of the game.
"I have looked at the video and although it's not a great view, the lad (El-Abd) stopped Rickie getting up. It's a poor video but Lambert hasn't lashed out.
"The referee had a better view and there's no doubt it was a defining point.
"We need to win the next one. We're being challenged from a results point of view."
Brighton manager Gus Poyet said:
"There is no better way to start the year. From a fan's point of view, apart from the win against Crystal Palace, it doesn't get any better.
"I'm delighted with the result after our recent run of results. It's all about decisions and fortunately they worked well so I'm pleased."
Full Time The final whistle is blown by the referee.
Corner taken left-footed by Daniel Fox, clearance made by Matthew Sparrow.
Free kick awarded for an unfair challenge on David Connolly by Grant Hall. Direct strike on goal from the free kick comes in from Daniel Fox, Peter Brezovan makes a save.
Strike on goal comes in from David Connolly from the free kick.
Dismissal The referee shows Gordon Greer a red card.
85:06 Goal scored
Goal! - Matthew Sparrow - Brighton 3 - 0 Southamp'n Matthew Sparrow scores a goal from inside the area low into the middle of the goal. Brighton 3-0 Southampton.
Corner taken right-footed by Ryan Harley from the left by-line,
Substitution Ryan Harley replaces Kazenga LuaLua.
Ben Reeves challenges Grant Hall unfairly and gives away a free kick. Peter Brezovan restarts play with the free kick.
David Connolly takes a shot from close range clearing the crossbar.
Assist on the goal came from Liam Bridcutt.
75:59 Goal scored
Goal! - Matthew Sparrow - Brighton 2 - 0 Southamp'n Matthew Sparrow scores agoal from 35 yards to to the top right corner of the goal. Brighton 2-0 Southampton.
Jack Cork gives away a free kick for an unfair challenge on Kazenga LuaLua. Direct free kick taken by Liam Bridcutt.
Grant Hall gives away a free kick for an unfair challenge on David Connolly. The free kick is delivered left-footed by Daniel Fox from right by-line.
Kelvin Davis takes the free kick.
Substitution Ben Reeves is brought on as a substitute for Adam Lallana.
Booking The referee cautions Matthew Sparrow for unsporting behaviour.
Jos Hooiveld fouled by Matthew Sparrow, the ref awards a free kick.
Effort from just outside the area by Steve Cook goes over the target.
Will Buckley decides to take a short corner.
65:59 Goal scored
Goal! - Jake Forster-Caskey - Brighton 1 - 0 Southamp'n A goal is scored by Jake Forster-Caskey from deep inside the penalty box low into the middle of the goal. Brighton 1-0 Southampton.
Kazenga LuaLua takes a shot. Save made by Kelvin Davis.
Daniel Fox concedes a free kick for a foul on Will Buckley. Will Buckley crosses the ball, Jake Forster-Caskey has a shot on goal from long range that goes wide left.
Substitution Jonathan Forte replaces Guly Do Prado.
Kazenga LuaLua takes a shot. Kelvin Davis makes a save.
Substitution Mauricio Taricco leaves the field to be replaced by Grant Hall.
Substitution Ben Reeves comes on in place of Guly Do Prado.
Dismissal The referee red cards Richard Lambert for violent conduct.
Effort on goal by Craig Mackail-Smith from inside the area goes harmlessly over the bar.
Short corner taken by Daniel Fox from the left by-line.
The referee gets the second half started.
45:00 +2:52 Half time
Half Time The first half comes to an end.
Free kick awarded for an unfair challenge on Jos Hooiveld by Liam Bridcutt. Daniel Fox takes the direct free kick.
Jack Cork takes a shot. Clearance by Liam Bridcutt.
Jake Forster-Caskey takes the direct free kick.
Substitution Dan Harding leaves the field to be replaced by Daniel Fox.
Foul by Jack Cork on Jake Forster-Caskey, free kick awarded.
Foul by Guly Do Prado on Jake Forster-Caskey, free kick awarded. Liam Bridcutt restarts play with the free kick.
Free kick awarded for an unfair challenge on Will Buckley by Dan Harding. Centre by Will Buckley, Kazenga LuaLua produces a right-footed shot from just outside the area that goes harmlessly over the target.
Adam Lallana takes a shot. Save by Peter Brezovan.
Corner from the right by-line taken by Dan Harding, clearance by Liam Bridcutt.
Liam Bridcutt takes the free kick.
Booking Dan Harding is shown a yellow card.
Unfair challenge on Craig Mackail-Smith by Dan Harding results in a free kick.
Close range effort by Guly Do Prado clears the crossbar.
Effort on goal by Steve Cook from inside the penalty box misses to the right of the target.
Dan Harding takes the inswinging corner, clearance by Craig Mackail-Smith. Jack Cork takes a shot. Peter Brezovan makes a save. Adam Lallana takes a shot. Peter Brezovan makes a save.
Jake Forster-Caskey challenges Dan Harding unfairly and gives away a free kick. Direct free kick taken by Dan Harding.
Gordon Greer is caught offside. Kelvin Davis takes the direct free kick.
Free kick awarded for a foul by Dan Harding on Will Buckley. Liam Bridcutt takes the direct free kick.
Dan Harding gives away a free kick for an unfair challenge on Will Buckley. Direct free kick taken by Steve Cook.
Guly Do Prado handles the ball and concedes a free kick. Free kick taken by Gordon Greer.
Free kick awarded for an unfair challenge on Kazenga LuaLua by Aaron Martin. Kazenga LuaLua crosses the ball in from the free kick, David Connolly gets a block in. Kazenga LuaLua takes a inswinging corner from the left by-line to the near post, Aaron Martin manages to make a clearance. Kazenga LuaLua takes the inswinging corner, clearance made by Richard Lambert.
Unfair challenge on Jake Forster-Caskey by David Connolly results in a free kick. Liam Bridcutt restarts play with the free kick.
Unfair challenge on Jake Forster-Caskey by Jack Cork results in a free kick. Liam Bridcutt takes the free kick.
Inswinging corner taken by Adam Lallana.
The referee blows for offside against Craig Mackail-Smith. Jos Hooiveld takes the direct free kick.
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