Brighton produced a classy attacking display to ruin Nathan Jones' first Premier League home game as Southampton manager and run out comprehensive 3-1 winners.
Adam Lallana flicked in Solly March's cross before Pervis Estupinan forced Romain Perraud into an own goal. A stunner from March ten minutes after the restart effectively put the game to bed, though James Ward-Prowse did nod in on the rebound after he had a penalty saved by Robert Sanchez.
Brighton started in breezy fashion as Kaoru Mitoma jinked past a few challenges and powered an effort towards goal which Bazunu turned behind.
Their enterprising play was rewarded inside the opening 15 minutes as Lallana directed March's cross towards Bazunu, who could only flap at the ball as it fizzed past him and into the back of the net. It was the first goal Lallana has scored against his former club.
Southampton started to throw a few jabs of their own, with Ward-Prowse sending a free kick whizzing past Sanchez's post, and pressed the visitors well to win a few corners. However, end product eluded them and Jones' side were soon two goals behind through a rapid counter attack.
The Seagulls drove up the left before Estupinan crossed into the box, where Bazunu flicked the ball into Perraud. The Frenchman stumbled over the ball and his attempted hack under pressure from March resulted in an embarrassing own goal.
Southampton's lack of a game plan became more evident as Che Adams chased lost causes up front, while Brighton came close to a third on two occasions through Mitoma. He headed over on the break and then nearly set up March for a tap in, only for the ball to fall behind the Englishman.
The home side created their best chance of the game shortly after the break as Samuel Edozie twisted and turned in the box only to send a shot well clear of the bar.
The atmosphere at St Mary's became ever more anxious and groans more audible when March belted in the third. The winger drifted infield and unleashed a barnstorming strike from outside the box which left Bazunu grasping thin air. It was his first Premier League goal since 2020/21, having failed with 27 previous shots this season before Monday afternoon.
Mitoma sent a free header wide with the visitors looking more likely to add to their lead, but Edozie did give Ward-Prowse the chance to claw one back from the spot when he won a penalty off a challenge from Pascal Gross.
The Southampton captain's effort was saved by Sanchez back to Ward-Prowse, who stooped to nod in past the agitated Spaniard. However, new manager Jones couldn't muster a grandstand finish from his side as Roberto De Zerbi's team comfortably saw out the final few minutes.
The win takes Brighton up to sixth in the Premier League table, six points off the Champions League places, while Southampton are down in 19th thanks to their fourth league loss in a row.
Southampton player ratings
GK: Gavin Bazunu (5); RB: Kyle Walker-Peters (6), CB: Lyanco (7), CB: Mohammed Salisu (6), LB: Romain Perraud (4); CM: Ibrahima Diallo (6), CM: James Ward-Prowse (7), AM: Samuel Edozie (7); RW: Mohamed Elyounoussi (7), ST: Che Adams (6), LW: Moussa Djenepo (6)
SUBS: Joe Aribo (6), Stuart Armstrong (6), Ainsley Maitland-Niles (7), Sekou Mara (6), Adam Armstrong (N/A)
Brighton player ratings
GK: Robert Sanchez (7); RB: Joel Veltman (8), CB: Lewis Dunk (7), CB: Levi Colwill (7), LB: Pervis Estupinan (7); CM: Pascal Gross (7), CM: Moises Caicedo (7); RM: Solly March (9), AM: Adam Lallana (8), LM: Kaoru Mitoma (7); ST: Leandro Trossard (7)
SUBS: Jeremy Sarmiento (6), Evan Ferguson (6), Tariq Lamptey (6), Billy Gilmour (N/A)
Player of the match - Solly March
*Ratings from Fotmob
Source : 90min