Match ends, Southampton 1, Brighton and Hove Albion 2.
Brighton boss Graham Potter says Sunday's victory over Southampton has given the Seagulls "renewed belief" they can retain their Premier League status.
Leandro Trossard's emphatic finish settled an entertaining south-coast contest, Danny Welbeck's deft touch freeing the Belgium winger to stride into the box and lash home.
Victory halted a three-game losing streak for Potter's Seagulls, who climb a place to 16th above Newcastle, three points clear of 18th-placed Fulham and with a game in hand.
"We've had to suffer recently but we got the reward for the performance," said Potter, whose side have lost 17 points from winning positions this season.
"This three points gives us confidence and renewed belief. It's a fantastic reward for the players and will help them keep going.
"We have belief in ourselves and believe that if we keep performing like we have been we can get results. It's nice to have that reinforced."
The Seagulls had taken an early lead through skipper Lewis Dunk's powerful header from a corner before Che Adams' close-range volley ensured the Saints headed in level at the break.
Adams came closest to a second equaliser for Southampton, still without injured leading scorer Danny Ings, but he was brilliantly denied by the outstretched leg of Brighton keeper Robert Sanchez.
A 10th defeat in 12 league games keeps Southampton in 14th, very much in the relegation mix, although they still have a seven-point cushion over Fulham.
Seagulls finally take their chances
Three successive defeats in a five-game winless run had dragged Brighton back into relegation trouble after back-to-back victories over Tottenham and Liverpool had seemed to move them clear.
Two of those defeats - by West Brom and Crystal Palace - came in games the Seagulls dominated, recording an aggregate shot count of 29-8 in a microcosm of a season in which they should surely be several places higher.
They were nowhere near as superior at St Mary's but, for once, made their better chances count, particularly Trossard's as he kept his cool to send Fraser Forster the wrong way one-on-one after Welbeck touched on Adam Lallana's clever pass.
Lallana was influential throughout against his former club, drawing particular praise from Potter, who said: "I thought he was fantastic today.
"He takes the ball in tight areas, links the play up really well and uses his voice to organise the team. He's a really important player and person for us."
Saints keeper Forster had produced fine saves to thwart Neal Maupay shortly before Dunk's opener and Pascal Gross, with his leg, at the end of the first half as Brighton carved out the game's better openings.
This was the first time in 11 Premier League games that Brighton had scored more than once and the fact centre-half Dunk, now on four goals for the season, is their second leading scorer behind Maupay, tells its own tale.
The Brighton skipper was more than 12 yards out when he met Gross' corner but superbly guided his header out of Forster's reach into the bottom corner as Southampton paid the price for not having a man on the post.
After Trossard restored their lead, Brighton saw the game out comfortably, their only scare a late penalty appeal after Kyle Walker-Peters went to ground but, unlike December's reverse fixture when Saints won via a late spot-kick, the video assistant referee ruled there was no foul.
Another setback for sorry Saints
Southampton have not won at home since 4 January when they beat reigning champions Liverpool to much fanfare, although the Reds' subsequent struggles have arguably cast that victory in a different light.
Much has been made of their rotten recent run but they have had a tough sequence of fixtures against top-half sides, with both Manchester clubs, Leicester, Arsenal, Aston Villa and Everton among their conquerors.
Nonetheless, they have collected just four points from the past 36 available which is relegation form in anyone's book and Ralph Hasenhuttl will be concerned by how devoid of ideas they looked after falling behind for a second time against Brighton.
Their only real chance of a response came three minutes after Trossard's winner, Sanchez superbly denying Adams after referee Stuart Attwell had played advantage for a foul on the edge of the box.
The continual improvement of Adams was Saints' biggest chink of light - he scored for a third successive game and is beginning to look like he belongs at the top level after a slow start to his Saints career.
However, their troubles continue at the other end - Saints have now conceded 32 goals in 2021, more than any other Premier League side and that is something Hasenhuttl must remedy if his side are to avoid being dragged further into danger.
'One of our worst games' - what they said
Southampton manager Ralph Hasenhuttl speaking to BBC Sport:
"In the second half the opponent wanted it more and we have to be self-critical about it because it was by far one of the worst games we have played this season.
"It is time to work on a few basic fundamentals in the next weeks. The second goal gave them a lift. Afterwards, we did not have a solution, only one chance at the end.
"We see that our game is far away from what is has been this season. I can remember we were one of the best home teams at the beginning of the season. What has happened in the second half, we have to ask the question ourselves.
"We are not hungry enough and the basics are missing at the moment which makes it very difficult to win games."
Brighton boss Graham Potter speaking to BBC Sport:
"I thought it was a deserved victory. Second half we got a really good goal and when we had to defend we defended against a really good side that plays with huge intensity.
"I felt quite comfortable second half, even though when the scoreline is that close you are never comfortable, so there were still a few butterflies."We have to not worry about anyone else. We have to focus on ourselves and getting the points. We haven't got enough points as it is so we have to keep working."It's a fantastic result from a performance that deserved three points. We have said that a lot [about our performance in matches] when we haven't got the points."
Dunk is Brighton's head boy - the stats
- Brighton have beaten Southampton at St Mary's for the first time since November 2009 - Brighton's Adam Lallana started for Southampton that day.
- Southampton have lost 10 of their past 12 games in the Premier League (W1 D1) - their previous 10 defeats in the competition were spread across 38 matches.
- Brighton scored twice in a Premier League game for the first time since a 3-3 draw with Wolves in their first game of 2021, with this their 11th match since.
- Lewis Dunk has now scored 20 league goals for Brighton, with 15 of those headers.
- Brighton's Pascal Gross has become the fourth German to record 20 assists in the Premier League, after Mesut Ozil (54), Leroy Sane (28) and Dietmar Hamann (22).
- Southampton's Che Adams has scored in three consecutive appearances for the first time in the Premier League - this is his longest league scoring streak since February 2019 (six for Birmingham).
Southampton visit another of their south coast rivals, Championship side Bournemouth, in an FA Cup quarter-final on Saturday (12:15 GMT).
Brighton host fellow strugglers Newcastle United in the Premier League, also on Saturday (20:00 GMT).
- 17ArmstrongSubstituted forN'Lunduluat 87'minutes
- 19MinaminoSubstituted forRedmondat 65'minutes
- 23TellaSubstituted forDjenepoat 68'minutes
- 33BurnSubstituted forZeqiriat 45'minutes
- 11TrossardSubstituted forModerat 86'minutes
- 18WelbeckSubstituted forPröpperat 77'minutes
- 10Mac Allister
- Stuart Attwell
- Shots on Target
Second Half ends, Southampton 1, Brighton and Hove Albion 2.
Corner, Southampton. Conceded by Joël Veltman.
Foul by Daniel N'Lundulu (Southampton).
Joël Veltman (Brighton and Hove Albion) wins a free kick on the left wing.
Substitution, Southampton. Daniel N'Lundulu replaces Stuart Armstrong.
Substitution, Brighton and Hove Albion. Jakub Moder replaces Leandro Trossard.
Corner, Brighton and Hove Albion. Conceded by Jannik Vestergaard.
Che Adams (Southampton) wins a free kick in the defensive half.
Foul by Ben White (Brighton and Hove Albion).
Jannik Vestergaard (Southampton) wins a free kick in the defensive half.
Foul by Andi Zeqiri (Brighton and Hove Albion).
Corner, Brighton and Hove Albion. Conceded by Fraser Forster.
Attempt saved. Andi Zeqiri (Brighton and Hove Albion) left footed shot from a difficult angle on the left is saved in the bottom left corner. Assisted by Joël Veltman.
Substitution, Brighton and Hove Albion. Davy Pröpper replaces Danny Welbeck.
Foul by Nathan Redmond (Southampton).
Adam Lallana (Brighton and Hove Albion) wins a free kick in the defensive half.
Attempt blocked. Pascal Groß (Brighton and Hove Albion) right footed shot from long range on the left is blocked.
Foul by Kyle Walker-Peters (Southampton).
Danny Welbeck (Brighton and Hove Albion) wins a free kick on the left wing.
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