It was Brighton's first win in eight matches having lost their previous six and drawn their last match against basement club Norwich.
It was back to back defeats for Mikel Arteta's team following their loss last Monday at Crystal Palace. It has placed a serious dent in their top four hopes as it coincides with a return to form of their North London rivals Tottenham.
Antonio Conte's Spurs' team moved up to fourth following their comprehensive 4-0 victory at Aston Villa.
Brighton will now hope to achieve their aim of a top four finish, while Arsenal and Tottenham's battle for Champions League qualification could well go down to the wire.
Man City retained their slender lead at the summit as their crunch clash with title rivals Liverpool ended in a thrilling 2-2 draw on Sunday.
Kevin De Bruyne fired the champions into a fifth-minute lead at the Etihad Stadium but Diogo Jota levelled eight minutes later for the second-placed Reds.
Gabriel Jesus restored City’s advantage before the break but Sadio Mane marked his 30th birthday with a second equaliser for Jurgen Klopp’s men.
Raheem Sterling thought he had put City ahead for a third time against his former club but VAR ruled against him in a tight offside decision and substitute Riyad Mahrez hit the post late on.
On Saturday, Raphinha underlined his value to Leeds as Jesse Marsch’s men took a significant step towards Premier League survival with a 3-0 win which pushed Watford closer to relegation.
The Brazilian – who has been heavily linked with a summer switch to Barcelona – stylishly ended a six-game goal drought to set his side on course for a vital three points at Vicarage Road.
In-form duo Rodrigo and Jack Harrison capitalised on some calamitous Hornets defending to seal victory as the West Yorkshire club moved nine points clear of the drop zone.
There were decisive wins elsewhere for Everton and Norwich City. Data experts at FiveThirtyEight have predicted how the final table could look...