Welling got the first win of the season after a great game at Melbourne Stadium and moved to the top of the table in the process albeit having played a game more.
Day made two changes to Saturday's side with Loui Fazakerley unable to recover from his dead leg with Ben Martin coming into the side as Fraser Franks moved to right back and Scott Kinch replaced Theo-Fairweather Johnson.
The Clarets got off to the better start as they took the lead on 18 minutes thanks to Craig Calver but seven minutes later the Wings equalised in some style.
Lafayette produced an outstanding goal on the volley from outside the box to draw applause from both sets of fans and Luis Cumbers completed the comeback with a typical poacher's goal from a rebound to give Welling a 2-1 half time lead.
An own goal 10 minutes after the break gave Welling that extra bit of breathing space and although Chelmsford tried their hardest to get back into the game it wasn't three minutes into stoppage time that Craig Parker pulled one back.
Welling's next match is another away fixture against Tonbridge Angels on Saturday before the Bank Holiday game against Sutton United next Monday.
By then it was too late and Welling had recorded another magnificent win against the Clarets in their own back yard.