Badshot Lea slipped to a 2-1 defeat at home to Horndean in the Isthmian League South Central Division.
Goals from Zack Willett and Kelvin Robinson were enough to give the Deans the three points at Westfield Lane, with Harvey Harry on target for the Baggies.
The Baggies created their first chance of the afternoon in the sixth minute, when Lamin Traore’s shot was deflected behind for a corner.
Kai Allsopp was next to go close for the home side on 18 minutes, when his shot was tipped behind for a corner by Deans keeper Lloyd Thomas.
Baggies skipper Baback Dehghani was next to try his luck in the 22nd minute, but his near-post shot went over the bar.
The visitors had a golden chance to break the deadlock on 26 minutes when Robinson was through one-on-one with Baggies keeper Harry Cawdron, but Robinson’s shot hit the post and the hosts cleared the loose ball.
Harry went close for the Baggies when he drove forward in the 36th minute, but his shot was easily held by Thomas.
The visitors broke the deadlock a minute later when Robbie Taw’s inviting cross was emphatically headed home by Willett at the back post.
Robinson had an excellent chance to double the Deans’ advantage on 43 minutes, but he poked his shot wide.
The Baggies pushed for an equaliser before half-time and Harry set the ball for Allsopp, whose shot was blocked. Dehghani got hold of the loose ball and worked some space, but his shot was also blocked.
The hosts had another chance before the break when Harry played in Allsopp again, but his shot was well parried away by Thomas.
The Baggies started the second half brightly and equalised in the 52nd minute when Harry showed good composure to go around Thomas and fire home into the back of the net.
The Deans regained the lead five minutes later when Cawdron saved Willett’s shot and Robinson emphatically fired home the rebound.
The hosts pushed for another equaliser, but were unable to find a second goal as they slipped to a third straight defeat in the league.
Next up for the Baggies is a home game against Isthmian League Premier Division outfit Cray Valley Paper Mills in the first qualifying round of the FA Cup on Saturday, August 31 (3pm kick-off).