Arsenal's hopes of Champions League qualification took a huge dent at home to Brighton & Hove Albion after a surprise defeat.
Leandro Trossard sparked panic inside the Emirates when he opened the scoring just shy of the half-hour mark with an emphatic right-footed finish from close range. The Gunners defence could only stand and watch as the ball trickled back to the Belgian for the game's opener.
Arsenal thought they had levelled things on the stroke of half-time when Gabriel Martinelli nodded home, but the Brazilian was deemed to be in an offside position after a VAR check that felt like it took an age.
