Albion lead Arsenal at the Emirates at half time.
Enock Mwepu, with brilliant support play, fed Leandro Trossard who fired into the top corner just before the half hour.
Albion have actually been on top. Mwepu, Marc Cucurella and Danny Welbeck have combined well throughout the half.
Moises Caicedo has also looked impressive on his Premier League debut.
Before the break Lewis Dunk made a great block to deny Arsenal’s Emile Smith Rowe.
Right on 45 minutes the Gunners appeared to have equalised as Gabriel headed home.
But the Seagulls went into the break with their lead intact after Gabriel’s effort was ruled out after a lengthy VAR intervention.
