Arsenal 3 Southampton 2: Gunners enjoy home comforts as Welbeck sinks Saints
Playing at home for a fifth successive outing, Arsene Wenger's side eventually prevailed in a see-saw contest to record their 150th league victory at the Emirates Stadium.
Welbeck was the hero for the hosts, the forward on hand at the back post to nod home Alex Iwobi's deep cross for the winner just moments after he had failed to convert a glaring opportunity inside the six-yard box.
The England international had found the net in the first half too, his deflected drive making it 2-1 after Pierre-Emerick Aubameyang's poked finish had cancelled out Shane Long's early opener for the visitors.
Substitute Charlie Austin appeared to have grabbed a point when he scored within two minutes of his introduction, the striker on hand to turn home Cedric's cross, but the Saints could not hold on and they remain in the drop zone, three points adrift of safety.
Jack Stephens saw red for shoving Jack Wilshere in the face in an eventful conclusion, while Arsenal also finished the game down to 10 after Mohamed Elneny's dismissal for violent conduct in the aftermath.