The 18-year-old inked his name in Albion’s history books with a brace before the break to edge his side towards their first continental berth.
Mohamed Elyounoussi made things interesting when he headed home to narrow the deficit in the second half, which also saw VAR chalk off a potential Saints equaliser before Pascal Gross put the game away.
Sixth-placed Brighton, who have a game in hand, could still finish level on points with Aston Villa below them, but their final-day opponents would have to overcome a near-impossible goal difference to finish above the Seagulls and clinch the Europa League spot.
The big occasion was marked by the appearance of a band from North Carolina State University who lifted nervous spirits in the sold-out stands with a rousing rendition of Sweet Caroline from trumpets and sousaphones.
Courtesy of GETTY IMAGES, here’s some cracking pictures from the Amex Stadium...
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Brighton and Hove Albion fans enjoy the moment at the Amex Stadium Photo: Mike Hewitt
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Richard Heathcote
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Richard Heathcote
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Richard Heathcote
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Richard Heathcote
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt
. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt
1.
Brighton and Hove Albion fans enjoy the moment at the Amex Stadium Photo: Mike Hewitt
2. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt
3. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt
4. Brighton 3-1 Southampton
Brighton 3-1 Southampton Photo: Mike Hewitt