Guillem Bauza rescued Swansea from an FA Cup giant-killing as the League One side came from a goal down to beat Ryman Premier hosts Billericay.
Guillem Bauza struck twice in the second half to rescue Swansea
Swansea almost led after nine minutes when Andrea Orlandi saw his chip headed off the line by Dave McSweeney.
But Wayne Semanshia gave Billericay a half-time lead when he pounced on Swans goalkeeper David Knight's fumble.
Bauza curled home the equaliser from 25 yards after collecting a long ball then poked home a winner from three yards.
Billericay: McMahon, McSweeney, Heffer, Blewitt, Kerrigan, Semanshia (Lay 57), Hunter, Dormer, Abbott (Hodges 86), Flack, Boot (Woods-Garness 75). Subs Not Used: Buckfield, Burbridge.
Goals: Semanshia 26.
Swansea: Knight, Rangel, Monk, Tate, Austin, Anderson, O'Leary, Britton, Orlandi (Allen 78), Duffy (Scotland 78), Bauza. Subs Not Used: De Vries, Lawrence, MacDonald.
Booked: Orlandi, Austin.
Goals: Bauza 59, 83.
Ref: Phil Joslin (Nottinghamshire).