Having made their strongest-ever start to a top-flight campaign, Brighton looked full of confidence in the early stages. Kaoru Mitoma shot wastefully wide after dispossessing Yukinari Sugawara while Georginio Rutter powered another effort agonisingly against the post.
The Seagulls continued to dominate proceedings and their pressure finally paid dividends in the 29th minute when Tariq Lamptey’s inviting delivery was brilliantly headed into the far corner by Mitoma.
Armed with all the momentum, the hosts went in pursuit of a second, however, it was Russell Martin’s side who spurned a glorious opportunity to level the scores when Cameron Archer missed the target from six yards after a superb cross from Sugawara.
Southampton were nearly made to rue that gilt-edged chance, with Joao Pedro seeing a low strike smartly saved by Joe Lumley on the stroke of half-time.
Determined to gain a foothold in the contest, the Saints knew a positive response was needed at the start of the second half.
Driven on by the influential Tyler Dibling, an equaliser duly arrived as Flynn Downes netted his first-ever Premier League goal, lashing home a rebound after Adam Armstrong’s initial effort was blocked.
Southampton thought they’d completed a remarkable turnaround eight minutes later when Archer converted from Ryan Fraser’s delivery, only for VAR to controversially rule the goal out for offside.
The match remained tantalisingly poised heading into the final 20 minutes, with both sides pressing for a late winner.
Dibling saw a low strike comfortably thwarted by Bart Verbruggen, while at the other end, Yasin Ayari blazed over the bar when well-placed in the box.
Despite a couple of half-chances in stoppage time, neither team was able to create anything of note, as Brighton missed the opportunity to move up to second in the table.
As for Southampton, they remain rock bottom after a seventh successive league game on the road without a victory (D1, L6).